i have a 99 ffv with a 5spd, 265/75/16, and stock 4.10's.... my truck has some getty up and go, for a ranger with bigger tires. i can get to about 65 -75, depending on the on ramp, and i am wrapping the engine to about 5k... like other people say, i dont shift below 2k, and rarely run it below 3k rpm's. i have troubles on hills in 5th, and have to shift to 4th to keep speed. but thats just how it is.
this is my first truck, and other than the 16-18mpg i love every little bit of it. the only thing i would want to do is maybe get a programmer, and get a locker for the rear, since i have a fully open rear end. both cost about $300-$400 each.
like other people are saying, your best bet with the auto tranny is to get a programmer to redo the shift points and get a few more pony's out of the little 3.slow. you have to remember this engine only has about 150hp.. thats the same as a 1000cc sport bike

haha.
so, just remember its a truck, not a hot rod.
hope you get it all figured out