i have a 1994 c/k 1500 with a new gm motor. and can not figure out my problem. My problem is that the truck will die out when idling or at a stop light once the truck warms up. although when cold it runs great no miss etc. the truck had the same problem with old motor also the last few miles before the swap. i have changed the ignition switch, fuel pump,maf sensor,etc any ideas on what will cause this kind of behavior????? thanks for any help or suggestions....

you ever figure this out? we have a truck with kinda same symtoms.

I would check your EGR valve. If it sticks it will make the truck run poor or stall at idle.

X2 on above post. Check the EGR solenoid too. Pull the line that goes to the EGR. You should not have vaccum to the EGR at idle.

turned out one of the plug wires on top the distributer just wasnt seated right just need to put a timing light on it now