@hayzer911 There's two generations of the 5.4, the first ran from '97-'03 and they're the 2V, two valves per cylinder. It isn't uncommon for them to spit spark plugs out because there's not a lot of threads, but proper torque helps a lot and if one does let go the repair kit is common and not that expensive. These are the 5.4s you want.
The second generation ran from '04-'10 and these are the 3V, three valves per cylinder. I'm on the fence with these but will generally echo the advice avoid at all costs. Cam phaser issues are the biggest issue with these and it's going to affect all of them, it's not if, it's when. And when it goes the best case you can hope for is it makes some unpleasant noises and you can replace them before anything worse happens. Worst case it slaps the timing chain against the case and sends aluminum shavings through the engine. This happened to my dad's truck. This generation also used two piece spark plugs that are notorious for breaking and being difficult to remove. Exhaust manifold leaks are also common (same for the 2v) not detrimental, but annoying and on the '04-'10 trucks very difficult and expensive to fix*. Of course all of that can be fixed with aftermarket parts and you'll have a solid engine, but with so many other options it's usually not cost effective. Aaaaallllll of that being said I actually really like the 5.4, both generations, as motors themselves. They make power and torque way down low and are excellent truck motors, far better than my 2014 5.0 despite the 5.0 being up 100hp on the earlier 5.4s, and 60hp on the later ones. It just doesn't make the bottom end.
*Because I'm already this deep in the rabbit hole. The 97-03 trucks used torsion bar suspension, and because of this there is access straight to the manifold through the fender well, it's tight and not easy, but possible. The 04+ trucks went to a strut design which blocks that side access, this means the motor has be lifted off the motor mounts to get any sort of access to the manifolds.
