Getting a p0304 code that just started recently. I know that it is a misfire on #4 cycl. I can clear the code and the car will run fine then I can feel it skip once then it will run fine for hours stop/start good acceleration etc. then the cel will come on with the p0304. The spark plugs were changed w/ Bosch 7955 FR7DC Super from FCP about 3000 mi ago a new cap, rotor and wires 27000 mi ago. I don't have any other codes and/or pending codes. The car has been running great w/ 237k on it. Could this be the sign of a bad injector?