Encountered a lost of power and rough running. I believed a cylinder or two have stopped firing. I thought the first thing I should do is to replace the plugs. When I removed the plugs today, I found the plugs in cylinder 1 and 3 covered with oil right from the stem of the plugs down to the electrolytes where the firing takes place. The oil on the dip stick looked normal (not milky) and the coolant level has not dropped or changed colour. Do you think it is just a bad rocket gasket that cause engine oil to filled up the plug Walls and only started flowing down to the electrolytes when I was removing the plugs or do you think there is a more serious issue e.g worn piston rings, blown head gasket, blown valve seal etc??