How do you know if you have fuel starvation or another problem? I was pulling only around 8000 lbs up a slight incline and after about 45 seconds I got a stumble from the engine...let up and it went away, no engine lights. Had the Predator 65 tune in; stopped and put the 40 tune in. Checked codes; had one for fuel temperature. Cleared it and drove with the lower tune in--it did stumble again later. It seems as though it's running out of fuel...I don't think it's turbo bark because the throttle was steady. Stumble only lasted a second or so. :(

Truck has Banks intake and exhaust, a Racor fuel pre-filter, boost stick, and of course the Predator. 05 LLY. Thanks for any info.

I would try and put the tuning back to stock, completely before diagnosing any further. That'll rule out the tune, right from the get go.

When's the last time you changed your fuel filter?

Ok. Fuel filters are new. Forgot to mention I was doing about 64 in 5th.

Thanks