Here we go again, My 92 K1500Sub still has issues, No codes from the OBD, New dist, new coil, new FRP, new IAC Valve, New fuel pump, filter & strainer. Truck runs smooth and strong but stalls at idle when put in gear at my wits end and not wanting to have dealer fid problem.......(sigh)

Looking at my 90 FSM, it lists the following at possible causes:

EGR Valve
PCV Valve
TPS
IAC (I know you replaced it but this you make sure that the inside of the TB was clean where the IAC goes)
MAP Sensor

My 90 has 108K and I just put a new EGR in it since I had to pass a smog test. If you have the original EGR with over 100K, it can't hurt to replace it.

//2000CAYukon

so the truck runs fine other thanwhen you put it in gear huh? :confused:

crawl under the truck and unplug the lock up switch on the transmission. i have seen cases where the lock up switch inside the transmission will hang up and cause the motor to shut off when put in gear but run fine while idling in park. give it a try...it wont hurt a thing to see if thats the problem. lemme know how it goes :grinyes:

Will this cause a fault code, Because in reading the diagnostic codes all is well. Also which plug would be the lock up solenoid? Just to clarify the truck idles smooth in gear and will have and occasional stumble almost dies and then something in the truck brings the idle up to keep it from dying. It is not constant but happens enough to not want to drive the truck. It is very annoying, The truck doesn't just die when in gear, It will idle fine but will get the stumble and either stall or cause it to lurch once the ECM gives it more fuel as if compensating for the drop in fuel? Again no fault codes off the OBD system.

I agree with chahonda. I remember ghearing something about the electronic lockup sticking and when you put it in gear it wil kill the engine, kinda like trying to start off in high gear.

If the tranny is electronic, try unplugging every connector and drive it. It will go into "limp-in mode" which will give you park, neutral, reverse, and direct drive. From what I've read, I would have to lean toward something dealing with the tranny. Perhaps wires touching together and telling it to go into 2 gears at once? This is just a wild guess, but since it's been about a month, it's worth a try.