Cuts out going up hill.

Byron, my truck was doing that. Exactly as you describe. I very carefully went over the whole fuel system and found the culprit. The rubber hose from the sending unit to the hard line was very, very soft and I suspected that it was sucking shut. I replaced all of the sections of rubber hose with Gates Barricade EFI hose and the problem went away. It's worth a look.
I will look at that hose it is not that old but I know its not efi rated just normal fuel line