I have a 2004 f150 4x4 with the 5.4. All in all not too bad of a truck. I have around 80000 miles on it. The cam phasers had to be replaced on both sides once it started to sound like a diesel. It was under extended warranty, but the stupid thing was they would only replace the noisy side. So the second set were done at a later date once they started ticking. I also had the rear axle seals go out on both sides. Once again the warranty would only cover one side at a time. Stupid. They were replaced within two weeks of each other. New gear oil each time...what a waste. It has had a couple of minor recalls. The latest was something involving the driver side air bag. And just last week, off warranty, I had to replace the throttle body. A $500 bill.
I use it alot to tow an enclosed trailer packed with band gear. It is a hog on gas and doesn't matter if I am towing or not. I think the best I ever got for mileage was around 17mpg. I think it is mostly around 14.
I also have an 82 tacoma with 350,000 + miles that has been on its top twice, the doors don't close properly, it has wind noise like crazy and the rust weighs more than the rest of the steel. But the little sumbitch will not stop running. So I definitely have a soft spot for the tacomas.