Champion plugs are only good for lawnmowers and Chryslers's. The OE Motorcraft plug is designed and tested by FMC for specific engine for best performance. In my line of work I have been to enough engine performance classes and all the engineers tell us the same things in every class,use Motorcraft(ford),AC Delco(GM),and Mopar(Chrysler). Yes autolite makes motorcraft,Champion makes Mopar and denso makes Delco but the aftermarket brands have slightly different heat ranges. It is also very common for those direct ignition coils to go bad and have more than one go bad at the same time. Coils come with the boots but if you just have a boot with a hole in it they can be bought seperatly.