1.6 16v has slight stumble

[fixkick]

welcome, all Suzuki and Geo's are
welcome,

Hi I am new to this site and was hoping you could offer a best guess to my problem.
I have a Samurai that I put a 1994 1.6 16v in and recently barely failed emissions due to high nox.
(The nox was close too passing)
I followed the advice and was able to clear the EGR passageway which was plugged and now pass a stall test. The valve passed the hold vacuum test also.
This vehicle has a hollowed out cat and I know that's a no no! (that kills EGR 2ways (TWC nox funcition in cat) and kills back pressure to EGR modulator.

I have a new cat and will install it along with a new O2 sensor I bought.

The question I have is the engine has a little above idle stumble when I let out the clutch and take off but it only occurs during take off like under a load.
Be sure to calibrate the TPS correctly. but this can be the EGR messing up.
I disconnected the vacuum line to the EGR valve as a test and the stumble is gone. (with it sucking air or plugged up that hose?)
Do you think the new cat will take care of this issue, because there now be more back pressure? (yes, the ECU is tuned for working EGR)

If the cat does not solve the stumble issue would it now be reasonable to suspect that the EGR valve may have a weak spring causing it to open
pre-maturely?
Thanks for all advice

I dont think that spring is weak..
The EGR mod is not working now or is acting wrong or weak.
A good cat will , wake up this old EGR mod and it will work if the red vent path is clear.
the mod never goes bad, just the vent paths can get dirty.
NOX 101:
if the engine is running good, holds closed loop at idle and light flat steady foot cruise, the engine nox will be very low (out to CAT)
and what remains the CAT eats all that up (catalyzes it)
see this guy get NOX 24 and then next guy 1 ?
http://www.fixkick.com/smog/smog.html

the state laws are loose for NOX, one state allows. 800ppm. huge, amounts, and even a weak cat can pass that.
a new cat will zero it. or close if the EGR works, and The EGR modutator works (live test passes)
the 1990 car is not even tested for NOX. (no TWC)
but your's is. and at 25mph on tire load rollers....
Get smog passing first , i bet the tiny hicup's end.




GOOD LUCK!