2001 HD 8.1 Problem

[usafdaytonan]

I've got a 2001 Hd with the 8.1, Allison tranny, and 4:10 gears just turned 160k with no major problems. When i'm on a long drive with the truck (over an hour or so) it starts to sputter and want to shut off, I have to mash the gas to get the truck to respond and once it gets back to speed it starts doing it again. Last time it did it for 40 miles till I got home, shut the truck off and the next morning it was fine. The check engine light doesnt come on but the ABS and E brake lights have not neccessarily whent he truck is acting up. I have a supretech tuner for it, but the truck was doing it before I got the tuner and the only code the tuner reads is the engine torgue signal circuit which is a tranny code. Any heads up would be much appreciated before I sink a fortune into a mechanic. The last one I took it to, the truck never did it for him because he never drove it for over 30 mins.