I have a 1989 Silverado that I replaced the motor around 20,000 miles ago and since then I have had an issue with the truck dying when sitting at idle at stop lights and when shifted into reverse. It doesn't happen as much when the truck is cold, but very frequent when warmed up. I took it in to auto electric shop 6 times and they could not isolate the issue. I have changed the TPS recently and that did nothing. I have had 3 different mechanics check it out and no one seems to have an answer. Please let me know if anyone has input.

 

I had a buddy with a 99 that died when he put it in reverse with the headlights on, it had a body lift and one of ground straps wasnt put back bc it was too short...he replaced the ground strap and its been fine ever since. i guess the extra load of the head lights brake and revese lights killed power to the fuel pump or ignition coil....maybe your missing a ground strap somewhere...or have one not making good contact.....hope this cures ur problem....good luck

 

my 94 silverado would do the same thing. stall out at a stop, then take half hour or so before it would restart. shops couldn't figure it out. $2500 later i found out it was the torque converter lock up solenoid. i think it cost around $60 including gasket for trans pan and about hour to replace