93 suburban stalls after idling for 10 or 15 minutes. It acts just like the fuel pump stops, but I have fuel at the throttle body and the fuel pump runs and cycles like it is supposed to. I replaced the fuel pump and the fuel pump relay just in case, but the intermittent problem of it just stopping is still there.

I also replaced the Idle Air Control valve (IAC). When it starts it idles and runs great, doesn't surge, miss, or anything; then without any warning or indication it just stops. I have cracked the fuel line going into the throttle body and have good fuel pressure and flow, but it is like the two injectors just shut down. After it sets for quite some time, it starts right up and runs great, then, without warning, it just stops again. I am down to considering replacing the ECM, but I am not convinced that the ECM is the problem.

Any help with diagnosing this would be greatly appreciated.

I would replace the Ignition Control Module (igniter) and coil:

Zip Code Entry at PartsAmerica.com

Zip Code Entry at PartsAmerica.com

If you want, many AutoZone stores can test these componenets for free.

Sounds, to me, that the igniter may be breaking down under load, due to heat. Electron migration is a big factor causing these components to fail.

Check and make sure the coolant temp sensor isn't reading engine to be cold and still enriching.

Thanks for the great answers, I took your advice and replaced the ignition control module and the pickup coil and it has been running since then. It is however almost stalling every 5 to 10 seconds when stopped with the tranny in gear (like at a red light). It sort of cycles every 5 - 10 while stopped where it idles at about 800 - 900 rpm, then drops to 300 - 400 rpm for a second or two and almost dies. It does this over and over but if I shift into neutral the cycling stops.

I've seen a partially stuck torque converter cause a slow load-up and slowly decay the idle until stall occures. Try bumping the trans selector into neutral during the event and let us know what happens. Good luck!

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Originally Posted by okfarmer

93 suburban stalls after idling for 10 or 15 minutes. It acts just like the fuel pump stops, but I have fuel at the throttle body and the fuel pump runs and cycles like it is supposed to. I went ahead and replaced the fuel pump and the fuel pump relay just incase, but the intermittent problem of it just stopping is still there.

I also replaced the Idle Air Control valve (IAC). When it starts it idles and runs great, doesn't surge, miss, or anything; then without any warning or indication it just stops. I have cracked the fuel line going into the throttle body and have good fuel pressure and flow, but it is like the two injectors just shut down. After it sets for quite some time, it starts right up and runs great, then, without warning, it just stops again. I am down to considering replacing the ECM, but I am not convinced that the ECM is the problem.

Any help with diagnosing this would be greatly appreciated.

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Sounds to me like your carburator is set too low on idle, if you would adjust it while the vehicle is running it should help