HoosierinWA

So i have searched multiple threads and kinda mixed answer. I know that it could be several issues that can cause this problem. So a little history, its a 1990 Camaro RS with over 200,000 miles on the 3.1L V6. It sat for over a year and i purchased it from a guy who said he replaced the injectors and distributor. No dummy lights are on, I myself have changed the fluids, spark plugs from bosch to duralast. Replaced the EGR Valve, Idle control Valve and did Seafoam treatment,cleaned the throttle body. It runs great in the morning and once it warms up it wants to stall at every red light. I checked the vacuum lines and sprayed around to see if i could find a leak. No luck, Im about to replace the O2 Sensor cause i doubt its been changed in a long time. Could this sensor be causing my issues? Or possibly the TPS? I feel like i need to buy stock in Autozone as much time and money i spend there! lol any help/advice or criticisms would be much appreciated

Vader

Welcome Aboard!

When the throttle body was cleaned, was the IAC also removed and cleaned, or was it just cleaned off in place? What about the IAC air passages?

If it is not idling rough or misfiring, and simply stalling due to low RPM, the IAC would be the first suspect.

Changing out an old O² sensor is probably not a bad idea, but I doubt that it is affecting the idle speed.

HoosierinWA

Yes I have cleaned the passages a few times now, yesterday I replaced the starter which needed done due to bad heat soak. Discovered the cap was missing a bolt. Also I rotated it slightly and the idle sounds much better. Haven't had a chance to drive it far this weekend to see if it still wants to stall at red lights. Why did the Engineers decide to put the distributor behind the engine in the most awkward place to work on?

HoosierinWA

I've taken the throttle body off a cleaned it thoroughly with quetips

Vader

It still seems that the IAC may be sluggish, stuck, and/or not following ECM step commands. The IAC can be removed, disassembled, cleaned, lubricated, and reinstalled.

HoosierinWA

So i think i fixed it, as many of you know the distributor cap is located in the very back above the engine. I never noticed it but the cap was missing a screw. Which is a major pain to get too. Couldn't find a matching screw in stores, so just bought a new cap for $10 to get the screw, and have a cap ready for next time i need to replace it. Once the screw was installed and i rotated it slightly the idle got better, and stalling hasnt happened again. Also installed a new o2 sensor which might of helped too. As far as the IAC i bought a brand new one couple months back. Sprayed some cleaner behind the throttle body valve, and keep having tons of black stuff roll out of it. I have seafoamed it not sure what else i can do to clean it out more.