I have a 1989 Firebird Formula 350. I pulled the motor bored it .30 over to a 355, put a huge cam in .555 intake lift .535 exhaust lift, 1.5 ratio roller rockers, solid lifters, sportsman II 200cc heads. I rebuilt it and put it back in with the tune port injection and i cannot get the car to idle below 1500 rpms. How can I fix this issue and make the motor run correctly with the cam and mods?