bird stalling at idle

Hi, and thanks for reading. I have an 85 firebird 2.8 v6 and for about 4 years it has been stalling at red lights, stop signs, drive thrus...anytime I have to sit for more than approx. 3 minutes. This problem is much worse after a "second driving of the day", as in, from first crank to destination may only have a few problems, but if I have to cut the car off for a few minutes it is 10x worse. Usually it will act once like it's going to cut off, and if I continue to idle it finally dies. It always cranks right back up. So far, no check engine light has come on. My fuel pressure, fuel filter, IAC, MAF, distrubutor, plugs, wires, TPS, ECM, battery, alternator, and vacuum lines have either been replaced or checked. Also, my radiator fan ran constantly...up until a few weeks ago when it kept right on running for 15 minutes after I cut the car off (then it wouldn't come back on again, even when I needed it to). So, I then replaced the fan relay, and now we're back to running constantly. I have blown my own head gasket in my brain trying to figure out what this could be and the only thing I can think of is that maybe it's stalling right at the point when the fan SHOULD be coming on, but since it's already on, something is getting confused. Please don't be too technical with me, as I am a woman with very basic car knowledge. I have been to more shops than I can count, and nobody seems to be able to fix it. Arrrrrgggghhh!!!!

You replaced the ECM but did you replace the PROM chip? There was a known problem in the 85 & 85 PROM chips where they were exposed to light before the erase window on them was covered up. This resulted in a very slow corruption of the data on the chips and caused all kinds of driveability problems.

When sitting at the drive thrus is the vehicle in park or neutral and still stalls ? It seems there was a problem with the TCC solenoids on these.

Just a thought.

When sitting at the drive thrus is the vehicle in park or neutral and still stalls ? It seems there was a problem with the TCC solenoids on these.

Just a thought.
No, the TCC problems were related to the PROM chip also. I went through it all with my 85 IROC and finally found out there was a little known service bulliten out on the PROM chips, and it dates back to 1987. Of course GM won't tell you about it and they won't contact the owners to let them know (I am the original owner) even though they have all of your info, like address and phone #.

I'm not sure if the PROM was replaced also...I rather thought that was part of the whole deal!!! She only seems to want to stall in drive (or overdrive, as it were). I forgot to mention that she has about 22k on the engine and less than that on the transmission. I don't know if that matters in this case. One of the MANY mechanics that worked on her said it might be a transmission problem, so I took it to a transmission place and they said my transmission was fine (which I figured, since it doesn't slip or shift hard or smell funny). What was that TCC thing? By the way, a million thanks for trying to help me out!

I'm not sure if the PROM was replaced also...I rather thought that was part of the whole deal!!! She only seems to want to stall in drive (or overdrive, as it were). I forgot to mention that she has about 22k on the engine and less than that on the transmission. I don't know if that matters in this case. One of the MANY mechanics that worked on her said it might be a transmission problem, so I took it to a transmission place and they said my transmission was fine (which I figured, since it doesn't slip or shift hard or smell funny). What was that TCC thing? By the way, a million thanks for trying to help me out!
TCC is the Transmission Control Circuit. It is a solenoid that locks & unlocks the torqueconverter (lock-up converter) If the ECM was replaced then no, they didn't do the PROM chip. When you replace the ECM you remove the PROM from the old ECM and install it in the new ECM. The PROM chip contains all of the information needed to run a specific engine in a given application. And, yes one of the worst symptoms of the bad PROM was stalling in gear while sitting at a stop. It usually took 30 seconds or so once you come to a stop before the engine would stall.
Have you checked for stored codes in the ECM?
To do this, find the ALDL connector located down by the dricer's right knee, just barely under the dash. It has a 1" X 2.5" plastic cover over it, pop the cover off. Inside you'll see a connector. Find pins A & B (the upper RH 2 pins). Take a paperclip and straighten it out, then bend it in a U so the ends will go into pins A & B. Stick the ends in pins A & B. Turn the ignition switch on but DO NOT start the car. There will bw some clicking and other noises and the cooling fan will run, this is normal. Now, watch the check engine light. It will begin to flash like this Flash.....Flash, Flash (code 12) It will repeat code 12 3 times then it will move on to any stored codes and flash them out 3 times each. When all codes have been reported code 12 will repeat. turn the key off and remove the paperclip.
Post any codes you get here.

It coded a 12.
That literally means nothing, right?

It coded a 12.
That literally means nothing, right?
correct, code 12 means the ECM is communicating, no further codes means no faults were stored.