Hello, Scotty. I have a 2002 Chevrolet Prizm that keeps throwing a P0303 code.I have changed spark plugs, coil on boots, valve cover gasket and cykinder seals. The #3 cylinder did have oil in it but that is now gone. The new plug in cylinder 3 is firing, it looks to be carbon residue.

I can clear the code, start and drive the car without the code reappearing. However, when I turn the car off and restart it, the code reappears. Any thoughts on why it would do that?

swap #3 injector with another and see if miss moves. Pray it's that and not a blowing head gasket

I have swapped out the coil on boots and the misfire remains at #3. If the head gasket were blown, wouldn't there be a compression issue? The oil would be Grey also, which it is not. A leaking head gasket might be the issue but again there is no loss of compression. Couldn't it also be electronic? like a faulty sensor or bad ground?