have recurring check engine lite
had fixed by dealer at 98000 miles warranty fix.went back to catalytic converter.coil.plugs.wires.now at 107000 miles same lite and problem! lite stays on and test says I have a miss at number 4 plug. any ideas! was told dealers do not like to put much time in on warranty fixes.it all starts with engine running rough like a bad choke...same issue at different times...I do not want to go thru the same process again if I can help it.