All of the sudden started misfiring. I changed the spark plugs to platinum pre-gapped four prong plugs, it helped. But its still not firing properly. I checked all of the cop's and they were all firing. Could the cop's be bad even though they are firing? Should I replace those or save my money, because money is something I dont have alot of right now. I was told that the duratec's dont like platinum plugs, why? I dont know. I was also told that even though the gap spec is .51 , some duratec guys have luck with .6. Should I swap in those plugs instead of the platinums?