The way I understand it is that the problem stems from a couple of things:
1. Misinstalled from the factory, either under/over torqued.
2. 100,000 mile change interval is way too long, resulting in oxidation and corrision between the heads and the plug. When you go to change the threads can be stripped.
3. Consumers/mechanics not following specific torqing directions, you need a very accurated torque wrench, in lbs, for this job. Anything over or under will result in a plug shooting out, as the aluminum threads are not very strong.
I owned a 2000 f150 5.4 and never had a plug shoot out, and i'm sure that the problem is NOT that big, just from the sheer number of these engines sold it seems like a big problem, where in reality its probably a very small percentage.
These engines are much better than the 302/351/460 could ever dream to be. They're stronger, more efficient, and have much more potential power. And with these engines, its not uncommon to see them surpass 250,000 miles without any major problems, when properly serviced. The v10 is a beast compared to the 460, and the torque curves and peak torque numbers are much better than the previous gen engines.
/end rant.
