Lift pump!! I have the same truck and it didn't run for crap over LVL-6 before the lift pump. I drilled the fuel fitting's and shimed it, also added a AIRDOG 150 L.P. with tank pick-up. That works well enough for the fuel demand of the 350 tune. Even with all of that it runs out of fuel on the 425 tune.
Then back to level 6 it is for now....