rough idle 1996 g16b

[dkym]

Engine running:  https://youtube.com/shorts/_uOF4oSJshM

Me again.

I have a 1996 16v tracker (hacked up and converted to forklift) that I got with a swapped engine. 

She starts easily after priming and runs without stalling, but has a rough idle. The second video shows the engine, but doesnt capture the vibration.  It's not terrible, but a little too much to call ok. According to scan tool, idling around 800. 
Drives at low speed without issue.  A little bogging with sudden gas.
No check engine light, and diagnostics show no codes, which I find hard to believe.

Her last bout of non-running was apparently due to bad gas.  I switched "tanks", got a new fuel filter, cleaned up the pump screen. It ran after that. FPR was not holding vacuum so I replaced that, but that didn't affect the idle.

Sprayed starter fluid around intake parts to see if that would find a vacuum leak, but no change. 

The EGR valve, is that passenger side, by firewall, mounted sideways?  I can move the diaphragm, but it's not a thunk, it just moves.

Where is the IAC? ISC?

Thanks,
D

[fixkick]

Iac , is on bottom of TB throttle body 100% thermal device
the iSC is on facing engine right side of intake plenum bolted to it. and wired.
takes lots of driving to set many DTC codes,.P0300./
i bet the injectors are Filthy , how can they not be, they have 10micron screens inside, 4times smaller than the fuel filter. in fact.
in a pinch, try CHEVRON injector cleaner , for the gas tank, it has powerful benzine in it to clean those nasty injectors. (just chevron, other use, useless crap)
800rpm shows ISC and IAC are ok .
if IAC leaks rpm goes crazy high
ISC can be cleaned, easy. to make sure it is free of all gunk.
yes EGR like to leak and EGR is closed at idle fur sure. thus the clunk word. sure. but if CARBON IS THERE ON THE OLD NASTY SEAT IT WOULD CLOSE QUIETLY.
NEW EGR MAIN, WILL CLUNK

THIS ECU IS NOT VERY SMART , IT MAY SET p0171/2 ? FOR LEAN BURN. 171 IS LEAN. (OR P0300 CODES)
DO THE SCANS SHOW CLOSED LOOP MODE AT HOT IDLE?

MUST.

THE EGR CAN BE BYPASSED, FOR TESTING JUST MAKE UP A GASKET THAT IS CLOSED, 100%, BINGO NO EGR AND NO WAY TO MESS UP IDLE NOW.

NEEDS PRIMING TOP START YOU SAY?
COLD STARTS the PCM sees ECT cold, and sets the proper injection rates off real engine temps. rich.
and starts and runs easy if spark plugs not bad.
if not try using 5% right foot throttle to start the engine this add air to simulate a dead IAC><<< means IAC stuck closed dead. no cold start air.

[fixkick]

a clean MAF will help, using say CRC maf cleaner, nozzle 6" afar, not to close, spray 3 times, 2min rests between for it to soak in to gunk on the hot wire.
do not abuse the hot wire.or bump it.

[fixkick]

is that fuel pressure gauge I see,  that  is failing at 0.39 seconds, but the throttle must gunned to WOT hard and fast to see the PSI rise  6psi. and it must  or near.
this engine uses FPR, that sets fuel pressure  by intake plenum vacuum.
FPR has return line.  (bypasses fuel)
the charter is here, for oem FPR    actions

30psi IDLE
36psi key off (on,off ,on , 3 times) no start.  let the prime mode get  to 36
at idle gun  throttle and vacuum head to zero.
and see near 36psi.  , 6psi more than idle.  this 6psi overcomes  15psi atmospheric pressure. (sea level)

[dkym]

Thanks for the reply!

So, applying vacuum at egr causes stumble and eventual stall. That means it works, right?

Fuel pressure is running around 40 psi, WOT gives me around 45. The pump is old and is leaving rust particles in the gas even after cleaning. Maybe I ought to replace it. Fuel filter is new, but do I need to replace it again?

Once it reaches temp it does run in Closed Loop.

MAF reads at 3.2 g/s.

So, ISC and Techron next...

[fixkick]

sorry, I was not clear, yes EGR , hand forced vacuum (good EGR) makes RPM go to 400 RPM from normal; hot 800 and misfires vastly doing so. 400 shacks engine like wet dog does.
just closed the EGR main 100% and block the egr hose so EGR can not open again, as a test, even all week long test or years.
pump pressures good and wot too. 5psi rise. good.

rust i the tank allows rust tiny to walk past 40micron fuel filter and land on 6 ,10micron injectors screens (humans cant see)
and now injectors are partly clogged, and Injector balance test fails.
yes techron and pray;. yes.

misfire on good engines is bad spark or injectors dirty./
an injector shop pro that does injectors ,clean with reverse flow ,ultra sonic cleaner machines, to move the rust dust backwards out of injectors
yes pain , injectors can be, for sure any rust in the tank.
in the fuel loop , all.