I have a 04 cummins with a miss. I took it to a mechanic who killed each cylinder one at a time, and said the #6 injector was bad. I sent the injector off and it tested good. That guy said it may be in the wiring, but I'm not getting any codes. Is there a way to test the wiring that runs to injectors? Is there something else that may be causing the miss? The truck is bone stock, and always has been, no chips.