1989 454 crew cab dually

[2nd2none]

I've bought this truck last year to haul a racecar with and it is in good shape. First time I hauled my open trailer to the track I noticed that this fuel injected 454 has no power. Also it only gets about 5-6 mpg even without the trailer, it just s ucks the gas and lacks power. I've installed a new fuel filter, plugs and wires without any results. The truck idle's excellent, but when I'm taking off from a stop sign/light it hesitates until it gets some rpm's then cleans out. The check engine light doesn't come on so I dont know if the computer has any codes in it, nor do I know how to pull them either.
Anyone have any suggestions on what might be wrong with this thing? It's also my daily driver and going 20 miles to work one way is starting to get expensive
(1/4 tank of fuel just going to work and back home)