Problems running at operating temperature

[kevinc]

1988 C1500, 350 with auto trans. I owned this truck for several years and it never failed. I don't know where to now go with it. One morning last month, I drove it to work and 4 miles from home I was at a red light. Light turned green and the moment I touched the gas pedal to go, it died. No matter how much I tried to start it, it would not start. I had to get a tow home. Next day I started it and it ran perfect. I just let it run inn the driveway. Ran perfect for about 10 minutes, then the idle speed kicked up quite a bit. I don't have a tachometer, so I don't know how much. It ran like that for 5 minutes before I got in and touched the gas pedal. Instantly died again and would not restart.

What I have done so far...
It has good spark after it dies.
The spray cone from the injectors appear good.
I replaced the ignition module and ignition coil.

Still having the same problem. Runs perfect cold, but once it gets warm, it won't run at all.

I tried finding diagnostic info online, but can't find anything that matches my situation.

Any ideas?