Random stuttering and stalling issues

[immacomputer]

Hi, my '95, stock KA24DE, 240 has been pissing me off for over 6 months now with this lagging hesitation stuttering s***. Sometimes the car runs perfectly normal with no back firing or issues and then randomly while driving, it will start to stutter with constant throttle. When its in this mode, it will stall if I put in the clutch. If I keep it in gear and slow down, it will backfire extremely loudly at 2k and 1k rpm. It never backfires when running normally.

It's not throwing any codes anymore and I've replaced the distributor, O2 sensor, IATS, MAFS wiring, coolant temp sensor, spark plugs, cam position sensor, knock sensor, and timing chain. What could be causing this??? It's driving me crazy... I want to sell the damn thing but it probably needs to be running consistently to get any money out of it.

Any help would be greatly appreciated. I'm hoping it's not wiring issues but I'm out of ideas and my mechanic friends are also stumped and pissed off as it's making them feel stupid.

[Razi]

All your vacuum hoses look okay?
Is the EGR and other emissions equipment working fine?

[gnubberlang]

Does it seem to be related to engine bay heat? Might be worth trying a different ignition coil/module.

[GTR PrYdE]

I've a similar issue, ended up being stock injectors failing, some days would be fine, others it would sound like a sputtering WRX, it was only 1 injector though, and it happened again about a month later. You can test resistance between the injector pins and if its over 12 (mine were very high - 50 and 1000) then you know they're failing.

Not sure if that's your case but it's worth a check.

[immacomputer]

Thanks for the replies guys!

Vacuum hoses are good; we fixed a couple of them a while back and that helped with a constant idle issue. Now it only idles ghetto when it's in crazy mode. Other than that, it idles stable around 900rpm. The EGR is disconnected at the moment but because it runs fine most of the time, we haven't really suspected this to be an issue. I might still just replace it as it is not that expensive but since we don't have inspections here, I'm hesitant.

It's not heat related as it will happen either cold or at operating temp and it doesn't favor one or the other.

I will get on checking the injectors if my mechanic buddy hasn't already (I think he may have).

I do know that when it is in crazy mode, it's running extremely rich as the car doesn't smoke normally but will when acting up. It's a blackish smoke so I'm pretty sure that's rich and it smells gassy. Also, if it's doing it while I'm cruising, I can make it stop (albeit I don't have normal power) by throttling. I assume this is because I'm getting more oxygen in to help the extra gas combust. Definitely a loss of power though.