My brother had that same engine in his Ford truck.
Went to have a standard spark plug change done, cost him over $2,000 because the spark plugs had seized in the head.
The mechanic stated that if Ford would have put anti seize on the threads this would never have happened to so many engines.
yay Ford👎
Go Toyota
He got ripped off if they charged him $2000. They have a fairly inexpensive tool that extracts broken plugs from those exact heads. I did it myself on four stuck plugs. Each one took me about 20-minutes and two of those were the hardest to reach cylinders.
That said, the 5.4 is a solid engine. I've owned many and all had well over 200k miles when I sold them. Lots of torque down low where it counts. My personal vehicle has one with 258 on it. I checked compression when I changed plugs last time at 230k and all cylinders were nearly perfect. Taken care of, they should give you very few problems. A Ford mechanic friend of mine says he's opened them up to rebuild after 300k and the cylinder walls still have near-perfect cross-hatch patterns still visable.
One trick: if you have a 3-valve version (yours should be), use 5-30 full synthetic. The factory spec of 5-20 was to satisfy CAFE/mpg standards, but the cam phasers are much happier/quieter/perform better with 5-30.
