I recently had a 01 F250 5.4 blow a plug from the head. I repaired it with an insert. But what happened was when I tapped out the head for the insert and install the insert with the new plug. The insert went in too far, due to larger thread size of the insert. It had a misfire and actually burned the new plug and melted the bottom of the insert. Well, I got the insert out and installed another insert. But I still have a misfire. I don't know if it is the wrong plug or what. Compression is excellent and coil and injector are fine. Anyone got anything to share?