Auto Parts: Stalling, gmc sierra, cold run

Question
I have a 1990 GMC Sierra. It has 200000 miles and has started to intermittenly stall. Here is the situation: After then engine is warm (Not a cold run) the motor just cuts out as if I turned the key.(No hesitation/sputtering... just a solid shut down) I still have power. (After pulling to the side of the road I tried to start and the starter turned over) The first time that this happened I let it sit over night. When I returned I tryed to start it and it fired right up. Two weeks went by and the same thing happened. But this time it was a couple days before it started up. When running, it runs smooth and well.  It has new plugs and wires. New fuel pump. Any ideas?

Answer
Difficult to give you an answer from the other side of a keyboard without actually being there and trying some things...

Your description leads me to believe its electrical-related, most likely in the ignition system.  Maybe an ignition control module.  Some electrical part is working fine until it gets good and heat-soaked by the motor.  It's probably been through so many heat cycles it's on its way out.