2007 Jeep Compass, 2.4L 4 Cylinder, 140K miles
At idle, I randomly get a P0304. Sometimes a month will pass before I get it again. I have swapped the plug, coil, and injector with another cylinder. Still throwing a misfire from cylinder 4. I can certainly feel the rough idling and know when it’s about to throw the code. I never feel it during acceleration nor has it happened during acceleration.
I currently have the throttle body and intake manifold off the engine. TB was dirty, so I cleaned it with some carb cleaner. Noticed oil in the intake manifold, but apparently this is normal if it’s just a little. I plan on changing both gaskets and the PCV valve (although the valve seems fine). Once I reassemble everything I want to run some SeaFoam through the intake because the valves have some carbon build up. Not NEARLY as much as I expected to see from 140K miles, but I want to try and clear anything out.
Other than this, anything else I should be looking at while I have the intake and TB off the block? I inspected the head gasket, and I don’t see anything wrong.