Ok I think I am one of the unlucky ones who got a 5.4 with the head gaskit oil leak. When I was looking the truck over before purchasing, I saw some oil leaking down where the engine meets the manual trans. I thought it was a rear main seal going out. I got my truck for a song so I took the risk and naught it. Next I took it to a repair shop so the techs could use some die to figure out where exactly the leak was originating. They discovered it was feom the rear of the head. Needed to pull the engine to fix it. The shop quoted me at $3,200 to start and then go up from there lol. The truck had over 200,000 miles on it so I resided to put a remanufactured engine in. Had a local well known motor exchange shop swap in a new motor for $3,800. I figured that would eliminate most of any kind of problems I would have for a while lol ( spark plugs). I think the remaned motor should not have any of those problems. I believe it is an ARE motor. Hope this helps people looking at used 5.4 s. The oil leak is almost impossible to see.
Now it is time to doo some front end work. Ball joints ect.