turning up the fuel will give you a little more power, but mostly all it will do is raise the EGT's to an unusable level.
First, get more cold air in, via a home made or modified 5.2/5.9 Dodge cold air intake (not sure what years fit right) A free flowing K&N filter or comparable filter will help out too.
If you want to play with the fuel, install a pyrometer and I will tell you how to turn up the fuel...j/k. Seriously though, install a pyrometer and check out
this article on how to crank up the fuel....SMALL increments only!!
A bigger exhaust will help let the engine breathe. They do make headders for out trucks, I am not sure how good they are, maybe someone with them can post their expirences.
Make sure the truck is timed properly, the injectors, fuel filter and lift (mechanical or electric) pump are up to ***** and run a good diesel additive.
Also, little things like alignment, properly adjusted brakes, good U-joints and properly maintained wheel bearings will make rolling resistance less....increasing power as well (or letting the existing power do it's job freely)
Try one of them fart mufflers all the imports have.....they seem to think it adds power