94 Chevy Silverdo stalling

I have a 94 Chevy Silverdo 4X4 with a 350 that is stalling. It runs great on the highway but when you are in stop and go traffic it stalls a lot. It is even worse when the AC is on. It will run and not stall in park though. I replaced the plugs, wires, rotor, and Cap. Sent it to my mechanic and he did the IAC, ECU, Power steering pump, and miscellaneous grounds. I sent it to the dealer and after about 8 hrs and $400.00 he said I can't fix it. I don't know what to do next. The dealer did say he thought it might be the distributor. There is an older thread with the same problem but no fix. Can anyone help?

I take it there is no SES light on and no codes? Several things you might want to check: timing, check EGR valve (stuck), kind of sounds like it is idling to slow, what rpm is the idle on the tach?

A weak signal from the pickup coil in the dist can cause a stalling problem at lower idles. The pickup coil is encased in plastic and when the plastic cracks (due to age), the coil corrodes causing the pickup coil signal to be weaker.
The dist has to be removed and disassembled to see/replace the pickup coil.

A bad EGR valve or solenoid can also cause low rpm stalling.

Good Luck,
//2000CAYukon

It is definitly idleing slow around 500 - 600 in gear. What I noticed this morning is when it is cold and for about 5 -10 mins it's much better. It seems to idle hight then. After it warms up it gets worse. I'm not sure if it means anything but just trying to get all the symptoms out. I have thought about EGR before. I didn't think there was any way to change the idle since it is fuel injected. Thanks for the help.

Have you tried to clean the throtle body?

Throttle body was replaced with a known good one still same problem.

One thing that could relate it the temp sender.
When cold it runs good but when warmed up it doesn't.
Not a costly part.
Bob B

You will need a scan tool that can read engine sensors. Check O2 sensor, Temp Sensor, TPS position, MAP, Long and short fuel trim, then check injector balance, compression and cam lobes for lift.

UPDATE:

I figured I would add what the fix was. I ended up putting in a used distributor and that fixed the problem. I was something in the distributor that was causing the problem. The used one was 50.00 a lot easier then changing individual parts.