Approx 6000 mileas ago DTC for cylinder #1 misfire/out of balance 0301 developed. Have performed following repairs and diagnosis :
replaced plugs and wires (all 8), replaced both coil packs, cleaned MAF, IAC, confirmed #1 cylinder slow to fire via heat gun on exhaust manifold, compression test (all cylinders even - 165 psi), checked harness with Bosch test light plugged into #1 & #2 injector plugs - good, replaced #1 injector, no intake leaks. The only thing I've done that helped - temporarily wasn cleaning the throttle body and intanke with throttle body cleaner - sprayed 1/2 a can into the throttle body with the engine running. Even tried Seafoam in the intake, oil and gas tank. Also removed valve cover and checked the camshaft - it was good.
No smoking is present. Fuel economy has dropped to below 20 mpg - it is usually around 22 mpg.
Now the code moves from cylinder one to two every 15 to 30 miles.
Truck has 231k on it. I think I have a valve and/or head problem. Does anyone have any ideas? I'm looking for some help. Thanks