I have a 07 3500 with 108,000 miles. It has been a great truck. Lost an injector wiring harness last year in Kansas and replaced u joints last year also. Other than that has worked hard for me. Last week the check engine came on and truck started running poorly(no power). It corrected itself a few hours later, and few on/off cycles later. The check engine remained on, but it ran fine. Had my mechanic look at and he did a cylinder diagnosis to all 6. He pulled a cylinder 3 misfire code(I am pretty sure that is what he said) He said all 6 were at 100%. He cleared the check engine and sent me on my way. Today the same thing has happened. Check engine on, but truck running fine after a short spell of running poorly and multiple on/off cycles. I have obtained the codes from the dash and they are p0204 and p2149. I have found the codes on-line and what I found states 0204 is fuel injector 4 circuit and 2149 is fuel injector group 2 supply voltage circuit. My question is if this is multiple problems or another wiring harness. I am also wondering if it is a wiring harness again would it be worth while to replace all the harnesses to all the injectors while the valve cover is off. I plan on driving/owning this truck for a long time. Thanks