From a member over at my Suburban/SUV forum. He also owns a F150 and posted this
spark plugs for a ford 5.4, 3 pages20003 F250 V-10, spark plug change, 3 pagesWhat is the final word on Ford spark plug spitting, 4 pagesAnother sparkplug problem with Ford's 5.4 TritonThere are more, but thought these from my files covers the OP's TV
Such a poor design and IMHO, management decided to NOT spend the
tooling costs for a proper design
They just used the standard body and added that nose...which is what
breaks off due to build up of deposits between it and the head casting
Proper would have been to pay for the tooling to have the taper seal
seat extended waaaaaaay down there so that there is no cavity for deposits
to build up in
The blowing out of spark plugs was another issue and another poor
design metric
Aluminum head, so the number of threads for proper spark plug retention
requires more threads than cast iron
The head design done and to change the molds expensive. They did find
a way to increase the numbers of threads engaged to allow proper torque
for the plugs. Up till then, the manual spec'd torque was too low to
hold and also to prevent from stripping out the aluminum threads
