Well... I hope you didn't do like I did and possibly vapor lock the pump by installing the filter b/t the tank and the pump. That was only one part of my (potential) issues. Another part of my issue was it overheating. I won't emphasize that my external pump wasn't meant to be a "primary" pump (secondary pump that came from a ProCharger kit).

Starving for fuel is strong possibility. These tanks are not sump-type tanks, nor have baffles in them. If you got WOT from a stop, and the truck squats, then all your fuel surges to the rear of the tank. To be expected. The SUs are already less than 1/4" from touching the bottom. That's about as close as you'll get.