Get a cheap as hell set of copper TR55 NGK plugs..gap them to .055 and see if the helps. the super fine tip of the irids can cause a hot spot and detonation. Also.. it's time to swap those out. What about the wires?... don't be worried about answering a few things at once... I'm not the kind of guy to drag crap out of people.. I can nearly read minds through the internet...........wait.. stop having those thoughts...that stuff ain't normal!!!!