[War_Wagon]

I wouldn't mess with too much on the 5.0L, it is already a decent set up. The rockers are non-adjustable, and it has factory roller lifters, so the only thing you can really change is the actual camshaft, everything else can just stay the way it is in the valvetrain department. A cooler thermostat will increase performance, but decrease your MPGs. It makes more power because the computer always thinks the engine is a bit cold and tries to help it reach operating temperature by running it rich. I'd just advance the timing as much as you can given your driving conditions, fuel quality etc.

Electric fan is a good idea, the in-tank electric fuel pump is not something you have to change/upgrade until it gives you problems, don't worry about the stock alternator feeding the electric fan etc, they can handle it. An MSD system is always a good idea, these engines respond really well to them.

I think you will gain more from aero changes and driving changes than drivetrain changes for now. Some alloy wheels off an XLT model will save you some weight, consider trying a grill block, and if it wasn't a 4x4 I'd say drop it til the muffler scrapes, but a lowered 4x4 kind of defeats the purpose. Good luck.