I just put a '95 lt1 in a '96 firebird. During the switch I changed EVERY wiring harness in the car except the tail light harness. I bought the VATS box that matched my key. The problem I'm having is, when I start the car it dies after about 3 seconds. Start it again, it dies again. Same thing, same amount of time every time. I don't have to turn the key to the off position or let it sit for a few minutes. It restarts perfectly every time but dies after the same duration. The security light flashes while it's being started but does not stay on. Does anyone have the faintest idea to what could be done to fix this problem?

 

I found out that the computer is shutting down spark. Can anyone help now?

 

What ECM is installed?

 

The computer that came with the lt1 is in the car.