i have an 02 2500hd duramax/allison. i purchased it used a couple years ago. the previous owner had installed a 3 way bullydog module (stock, 75hp,150hp) k&n air filter, and magnaflow 4 inch exhaust with no cat. truck runs fine on all settings, but on 150hp setting under very hard acceleration the engine will stutter like its starving for fuel, and the trans will shift down to what seems like 3rd gear and stay there. then the service engine light comes on. pull over and kill the engine for a few seconds and everything goes back to normal. whats the problem? does the stock injector pump not supply enough volume or pressure? or does the stock intake system not supply enough air? or anyone have any other ideas? thanks.

i have an 02 2500hd duramax/allison. i purchased it used a couple years ago. the previous owner had installed a 3 way bullydog module (stock, 75hp,150hp) k&n air filter, and magnaflow 4 inch exhaust with no cat. truck runs fine on all settings, but on 150hp setting under very hard acceleration the engine will stutter like its starving for fuel, and the trans will shift down to what seems like 3rd gear and stay there. then the service engine light comes on. pull over and kill the engine for a few seconds and everything goes back to normal. whats the problem? does the stock injector pump not supply enough volume or pressure? or does the stock intake system not supply enough air? or anyone have any other ideas? thanks.

You need to give the codes the truck is throwing. Probably is starving for fuel with that tune. Some trucks can take it, some cant. Also, If you have no transmission upgrades you are asking for trouble. Your stock WILL NOT handle the extra power. This could be part of your problem also. Really need those codes...:)

Sounds like the tranny limped to me, time to upgrade