I put a 1987 Ford 302 truck (block) engine into my 1967 Mustang coupe. It's bored .30 over, roller 1.6 rockers, B303 cam, etc. I'm using the 1987 H.O 302 firing order. The problem is that I cant get the engine to run completely correct. I just replaced the spark plugs, but i'm only firing on 4 cylinders. I was wondering if anyone else had this problem and how to fix it because i'm lost. Basically the #4,5,6,8 cylinders aren't firing while the others are and again..... i'm lost. any help would be appreciated.