I have a 2002 F-150 5.4L. A few weeks ago #8 plug blew out when I started it in my driveway. I re threaded the plug and put on new coil. Truck ran great. A week later, #7 blew out. Again, the plug threaded, no problem, new coil and truck ran great. Three days later, #8 blows again. This time a new plug will not thread. After talking to some friends, and some research on You Tube, this seems to be a very common problem. So common, there are several kits available to fix this without pulling the head. I used Fix-a-Thred #98140T, about $150.00. I re tapped 7 and 8, new plug and was off smiling. The next day, #3 blew out. I have decided to park it, and re thread the remaining six. I ordered all new coils,( 8 Pack, Summit Racing #ACC-140032-8, $189.95), and all new plugs. I ordered extra thread inserts from Auto Zone #FIX98149P, about $30.00. Because the threads on the blown plugs were rusted, I chalk this one up to moisture, heat, expansion and contraction. I plan on using red thread locker on outer threads of insert, and a thread sealer on inner threads. By the way, this all started when I pressure washed my motor for the first time. Any advice would be greatly apprecieated.