240sxdriftin

ok i have been trying to figure this out for a few days and now i have nothing...so what happened is my wheels rubbed through the driver side harness in the fender well, it cut through 1 one wire and just rubbed the others, so it ran really crappy as if on 3 cylinders and we fixed the wire and it fixed the problem, so i drove home and did some other things to the car and went to drive again but it did the same thing it did before with the cut wire...so i checked and fixed every wire that got cut or stripped and thought it would be better but no...so we narrowed it down to the no. 3 injector is not firing, so i replaced that and its still not fixed, not i am out of things, and turned to you guys, so any help would be awesome thanks guys