My #3 sparkplug decided to come out on it's own again. This time it decided to take all of the threads on the cylinder head with it. Ford will not cover under warranty due too the mods on my car. Is this something that can be fixed (tapped) or do I need to do a head swap. The dealership wants $4,000 to fix, which I think is outrageous. Any ideas or suggestions are greatly appreciated. If I have to buy a new cylinger head, what other parts am I going to need to go along woth it besides the gasket? Where can I buy these parts?