I am trying to help a friend with a LS transplant into a 1993 pickup. It has been at 3 different shops with multiple changes and when he got it back it dies at the stop sign. I noticed when I lift off the gas the rpm's drop down and by the time I get to the stop sign the rpm's drop below the set amount sometimes it dies and sometime the rpm's will come back up and keep running. If I put it in neutral it keeps the idle. I dont have or he doesn't have the factory program from the computer. If anyone could take a look and see if anything stands out.