I have a 2011 5.7 and I’ve thoroughly enjoyed my truck.
A few things that I’ve learned....
“Cam towers” have a tsb I believe for leaks from assembly errors. Minor issue but worth looking for, the cam towers are essentially a girdle that’s holds the cams down onto the valves, you’ll notice a seam similar to a HG around each head, above the HG, but below the valve cover. I resealed mine, although they weren’t leaking....I was there anyways...
Timing chain tensioner - there is 4 of these suckers. I had one fail on me, not 100% but enough to cause odd noises here and there and apparently has happened a few times. I’ve intended to do a write up but haven’t gotten around to it.
Driveshaft - I have a 4x4 crew max, which utilizes a carrier bearing two piece shaft with a slip shaft as well, slip shaft causes a consistent thud on take off, remedy is to replace or for me I remove it and grease it every 5-10k. PITA and kinda annoying, but for some reason I’ve found this to be common on a variety of trucks. Ford even produces a special grease for this 10 years ago roughly to remedy their issues.
Exterior trim - I’ve notice the exterior pieces don’t hold up well, I (as well as a friend of mine) have had to replace all of the belt moldings along each door. Also along top window is coming loose on mine. Rubber antenna grommet rotted away long ago, replaced with new. Very minor, but nickel and dimes....
Rust - s*** these things rust if not cared for. Rough climates eat the frame and axle paint quickly, keep an eye on this...you should know toyota began replacing frames for northern climate victims....keep in mind when shopping.
Lastly, I love the size of my crew max interior....but I’d much rather have a slightly smaller cab in exchange for a bigger tank, and bigger bed. The 5.7 is a beast, I don’t have much experience with the 4.6, but they are nearly identical design.
Good luck!