i drive a 97 f150 with the 5.4 and i had a miss fire on the number 2 cylynder the guy said the whole the plug screws into was stripped and he had to put a spark plug with a gasket in it to keep the piston from tapping the gap in the plug shut. well that fixed that until now, now i can feel a slight miss while setting at a red light or just setting whilt the truck is running i think im fixin to have to replace the heads any suggestions on what kind to get i want some with a little more performance to them......

 

HI!... This kit can be done with the head still on the engine. I know because I did it.

http://www.timesert.com/html/Triton-repair.pdf