Stumbling and sometimes stalling after warm start?

The patient is a 1993 Chevrolet Caprice Classic, L05 TBI engine. Bone stock, and running on what are probably all the original ignition system parts. The car presently has just a touch over 90,000 miles on it, but has been doing this for a while now.

It doesn't seem likely to leave me anywhere, but I've been meaning to ask about this for a while.

When started cold, the engine always takes right off just like it should. If the car has been driven enough to be fully warmed up and left sitting for a while (say 30 minutes, maybe an hour), sometimes I'll come back to find that it'll fire right up, stumble for a bit and sometimes it will stall out. If it stalls out and I try again, nine times out of ten it'll start right up. The tenth time I might have to give it a momentary touch of the foot feed to convince it to stay running.

If it doesn't stall out, the engine will recover and sit there idling just fine.

It is never hard to start and drives just like it ought to. And I'm sure it would idle nicely all day if I ever asked it to.

Your thoughts would be appreciated. (I have a whole slew of ignition system related stuff I bought a long time ago -- plugs, wires, cap, rotor, maybe a fuel filter and probably a PCV valve -- just because I thought it'd be a good idea to change out what are probably 24 year old parts at this point. None have been installed yet.)

Mine started acting like that for about a month before the fuel pump died. Another thought: I think the EGR valve is prevented from flowing until the coolant sensor hits temp... perhaps it's stalling when it starts up.

Either way I'd go ahead and install those tune up parts since you already have them.

I have a similar issue, and I have not been able to find the cure. I have a new pump, replaced the engine with a 350 (was an LO3) including all of the sensors on the 350, and it still does it. I even put the computer from the donor car in it. Since I used the original engine harness, it must be in the wiring somewhere. I suspect the main engine harness, and possibly the part that loops under the front of the engine, although it could be anywhere. The part that loops under the engine has the wiring for the O2 sensor, temp gauge, purge system, and the rear washer motor. About the only thing I did not change is the spark control module on the right side relay bracket.

It is something that is not monitored by the computer, because I do not get any codes or CEL.

I am interested in finding a wiring harness for a 92 OCC with an LO5, or 92-93 RMW.

My trans would also stutter at about 45-55 when in steady traffic. I used some anti-stutter, and it stopped immediately. The trans has since died, and I am working on putting a modded L31 engine, and the trans out of my 91 in it.