i got my timing fixed put in a new intake (edelbrock performer) and new flow tech 1 5/8 headers i finally got the truck running after finding a bad wire when the motor started heating up all the paint burned off the headers except two when i tried to drive the truck it keeps backfiring i got a new rotor and cap new wires and can not figure this out please help the two cyls not firing are the two in the middle on the passenger side