cruise throttle surge

[fixkick]

(answering INLINE)
yes I have line 50 and both gaskets are new and tight
All lines are there and look to be properly located.

it is in my hand when I am putting vacuum to the port where the line 50 would attach. and it will not hold a vacuum. ( holding means what, a hand pump vacuum tooL?)
I can still not imagine what you are doing above.  hard line 50 has 2 ends,
Here is MAIN EGR mount, and the tube fitted up,  are you saying engine turned off key off, the EGR tube removed, you can not  pull a  vacuum with a hand too at the tube 50 port.?
or are you saying the TUBE 50 leaks air (always normal thata)   tell what test you do , now and if engine running or not, and level of disassembly for test.
The "S"bend Bark port, on the left goes to the left port (egr main IN) the out port goes to TUBE 50 only.  No body has path drawing inside  this intake man. Let me explain that.
what if you tired to test port 50 with the EGR removed, would the mouting holes like , GEE I DO NOT KNOW. (no drawing exists for this)
Test the EGR in hand only main in hand,  then test the EGR with EGR main fitted to the intake with gasket,
The EGR main mounted, will not bark at the out port engine running, if yes, then the EGR is good, the push in the magic EGR ring test, now it barks to port 50, end test EGR mail.



the year before this was QUAD port EGR injectors inside the intake MANifold and extremely hard to cure carbon clogs. this genius way means only pipe 50 clogs or up top, vastly more easy to service.  I call the GEN2 mono port EGR.
EGR can fail many ways,  (vacuum fails , exhaust fails) and EGR dead, , EGR WEAK and EGR stuck on (400rpm syndrom) and EGR works RANDOMLY.  yes, EGR is a pain.(can be)
that is why my EGR tests, show how to find most of those in fast simple tests.

The ECU has many modes, and the cold engine runs in the cold mode,  not to be confused with hot engine mode.  (EGR ONLY RUNS IN HOT MODE)
The OLD mode idle is controlled by that funny thing (IAC) below the TB,  it is 100% thermal mechanical part, not electrics.
then when hot the ECU and ISC (electric) takes over idle speeds, and loves to get dirty inside (ISC) and stick and fails to control hot idle at 800rpm (AC OFF)
400rpm hot, smacks of EGR main stuck open. (as they love to do but newer a new one)

I do not at al under stand your port pipe 50vacuum leak test at all , I what you did to do that, how, and with what tools (hand pump or vacuum gauge ) no idea at all  this. but seems to me done wrong, I test the EGR on the car mounted so there are no leaks, 

the valve was new in the box from o-Reilly auto. the second one was a warranty replacement. first cost $150 ish.
I will try the blocking of the 23 hose. '
I did put pressure on the exhaust side of the egr  (MAIN I presume) and got no leakage. ( EGR main in hand ?) GOod the valve closes, and expected, it is after all new EGR main.

So with no cat the egr will always show a code 51 because there is not enough pressure to operate the mod valve? (that is TRUE, and can be proven my EGR test page and the factory FSM book shows how to do that test and prove that fact. for sure.)

At Idle I have pressure that I can feel at the egr mounting flange where it comes out of the block. (I do not understand this line here, is this EGR removed? main?) IDK what you did.

how much pressure is needed to operate the mod valve.  0 to 2 PSI,  the full #4 exhaust port pressure is at FORCE HERE, that is how this works via the head tunnel EGR port.
not to say the egr was operating but it didn't throw any codes in the about year and a half that the cat had been gutted. ( THE egr TESTS ARE TRICKY HOW AND WHEN DONE)
THE ecu HAS PRESCONDITIONS FOR THE TEST, (HOT ENGINE, MOVING, AND GOING FAST, AND ENGINE LOAD MUST BE WHERE IT WANTS AND BAM CODE 51 TEST IS RUN.
IT ONLY LOOKS FOR DEAD EGRT AND HOT UNDER LOAD AND AT NO OTHER TIME.  OBD1 testing is covered in the FSM.



so putting a plate over the egr mounting boss should keep line 50 from leaking vacuum. ( keep in mind it took many posts until i saw you had pipe 50, ok:?) no photo of your
NO not this car, takes a tube 50 must Be blacked at the back side of upper tube 50 removed.
in other countries, Suzuki sells  a kit for this and sells cars like it, like Sold in SOUTH PACifica ISLAND or with VIN plate marked JDM version (I call them slicks, devoid of smog parts)
The car with pipe 50 needs 2 plates or just one hind the TB the port 50 mount at the top behind the main Plenum.

and plug the  exhaust port if I threaded the probe into that plate would that keep the egr code from appearing or is the resistor the only way to trick that?
The resistor trick works  EGRT in place (so it cant leak)  and then put said resistor across the 2 matching harness pins.  then the ECU thinks the EGRT is present. and is not.

I still need to drive this new egr and see if the code comes back and the Idle is still affected.

I just find it strange that the old egr was working or not throwing codes to be more specific. with the cat gutted.
1995.5 car is a one only car and this EGR system was faulty, the EGRT sensor proved be illegal in 1996, OBD2, because of many reasons but I can do 4.
1: it only tests for hot under load. (this is a bad idea. (can can be fooled easy. ) as the resistor proves .
2: the EGRT loves to pack in carbon and fail easy, (false reports, suck)
3: The EGR system was not tested for NON CLOSURE.  1996 the cut fuel test , was added, OBD2 EGR test B.
4: The EGRT does not really prove EGR is working at all ,  only that it gets hot, and never proves NOX reduction is working.

The test is lame and unreliable, kinda like trusting Carrier Pegeons for reliable communications... fail.  the next year ended this CALIF 95.5 EGR horror. 

one more reason for cat break up, the MUFFLER,  ends up with all  those chucks of CAT guts bricks landing the the muffler and blocking up its baffers causes back pressure.
or car this old has some wrong  muffler that is very restrictive, and making EGR work (amazing ,no, 2 wrongs make a right) This happens in EFI system. 2 sensor sensor failing can.

RECAP; and back on topic
new EGR (or pipe 50 blocked some way) plug the hose 23, with at golf tee, (easy way) screws work too but damage the rubber hoses.
now the EGR system is 100 % dead.
or just make plate for upper pipe 50, mount, block the plenum 50 port, with a plate , but this is more work. far far beyond hose 23 plug up for just a simple test.

All you are doing is proving EGR causes the idle problems or surge  or NOT.  (there are huge lists of reasons for that, not just EGR, EGR is only one cause)


now hose 23 and how it works for testing EGR, covered on my EGR pages, endless near. (stall tests. and bark tests and LIVE TEST !!!! ,etc)
PIPE #50 mount (dont do this) with welch plug pulled. clean the path from both ends, do not pull this plug


my new 96 exh manifold , and my trick to show, see here it is. clear as day.  this is the CAT back pressure SENSING PORT !


this is the bark tube path, to head tunnel to intake man, this is how EGR  ENGINE LOAD is measured using CAT back pressure, (large)  that is how this works, for sure.
On modern cars load is just MATH inside the ECU, (RPM/vacuum/MAF flows,and Throttle angles will get you ENGINE LOAD, as all 96+ cars do )

with no CAT present , Exhaust back pressure are NOT KNOW by anyone on earth, 1000s of mufflers sold and some glass packs and even no mufflers at all used offroad. endless.
UNDEFINED IS THE WORD. here.
the point of fact is the CAT must be present for EGR to work , the other fact is the EGR tests are poor, and lie to you, even with bad EGR shows all is happy.(tests)
the stall test is easy,  and not get burned fingers., see engine stall or on very strong engines goes to 400PRM.
we grab the trusty shop hand vacuum pump gauge tool (as seen and harbor freight for $30, or the old mityVac tool ™
then with hose 23 in hand pull a vacuum and see the diaphragm move in (a mirror needed on any 16v to see that) and then engine stalls, as my video shows on my EGR pages.
we also hand press the ring on the rear of the egr cold engine, with finger to see valve open and close,  all on car, and if those 3 tests pass. EFR main IS OK.(and leakdown on the diaphragm tests, as we always do on all diaphragms of any kind),, they do crack, and see of the valve also likes to stick, but gee yours is new.
a video of my EGR page, shows what it does,  (and engine with full compression spec, or not up on the rocky mountains will not stall ,just go to 400rpm or so)

seen here  https://www.youtube.com/watch?v=UPO7B7yH43w

The live test is covered in the FSM.seen here
here is the EGR (but uses po400 errors , in 1996 uP but works just the same, with no EGRT, uses EGR MAP.(fancy)

https://www.acksfaq.com/HTML/pdfs/96-FSM-v2-6e3-c7.pdf

chapter v2, 6e-3-c7 shows this, then the FSM flat fails to telly make sure the CAT is not missing or gutted,  (30 years later, gee, they are)


that is it, EGR testing is easy and vacuum tests are in the FSM./
the only hard test is the LIVE test ,, with car on 4 jack stands, very very carefully this test is very dangerous, with rear wheels going say 1mph. (not zero mph)
the ECU needs hot engine, and rear wheels spinning, and then looks at the VSS (veh, speed sensor) and if it clicks (over 0mph) EGR THEN OPENS, main.
That live test  is not easy, well is,  but dangerous.  best is on huge veh. lift safe and sound.

The hard EGR problems classic are those bark paths blocked 100 % or worst, 90% (carbon can pack any what it wants)
then CAT missing (2nd) I wonder how many of these old near 3 decade cars have a working cat, outside smog test zone, , ZERO?
no cat lasts 30 years. some even have welded on wrong CATS off 3 liter donor car, and fail.   only 2.Liter or less work here.
yours is 25 years old,  and that is OLD. (means expect anything, good ,bad , ugly, wrong or missing)

for sure good luck to you ,!!!