I've got a 2000 Silverado Z71 4X4 5.3 with 70K miles.
Occasional Problem: Starts immediately, but dies as soon as key is released from start position. After waiting 15-20 minutes starts and runs normally.
Truck has done this upon rare occasion (like once a year) for the last 15K miles. After such an episode, it might not be repeated for months.
Lately it's been doing it often, to the point of being worrysome.
The local dealer doesn't have a clue, and (typically) says that if it won't exhibit its problem while there they can't help. I fear they'll just start an expensive R& R procedure in a shotgun approach.