I have a 2002 F-150 5.4 with L type engine desided to replaced engine with a remanufactured due to cost of repair to fix bent exhaust valve. Not quite sure what happened but now it won't run for more than 12 seconds with a rough idle then dies out, if i try to give it gas sounds like it bogs and back fires then dies run better without giving it gas. According to what I have been told could a bad wire in in secondary ign, bad connector. Have checked wires in engine compartment found nothing bad also checked for continuity and all passed, connectors seem fine thinking it could be pcm although had it flashed still runs same not sure what to do next.