I know this thread is old, but I recently blew my 1993 4.3 and had a used 4.3L from a 1992 installed. The new/used motor does not have the air injection, but the mechanic use my old exhaust manifold and basically tried to braze over the fitting/hole on the exhaust manifold.
My question: Do I need to do anything to the motor? Does it need to be reprogrammed or anything?
Sometimes the truck seems to run great, other days it feels sluggish.
P.S. I always hear an exhaust leak somewhere, which could be coming from the brass braze on the manifold (it looks like it might have a tiny hole in it).
Cheers