Synyster

Hey everyone. Basically I finally got around with my friend to do the engine swap and we dropped in a 2002 gt motor. Started up fine after the whole thing, no leaks and all that but there seems to be a vacuum leak somewhere. I replaced all the hoses and everything is tight but my car is still misfiring (gunshot type misfires lol) and you could still hear a vacuum leak somewhere. I really just wanted to know if it's the manifold which is the only thing we haven't opened up, could I use the 98 npi intake manifold on the pi motor?

petrock

Gunshot style backfires are usually due to excess fuel in the motor and/or detonation inside the combustion chamber. It is probably a fuel system or spark timing issue not a vacuum leak.