2004 F150 Power Loss

I have a 2004 F-150 with 458 hrs on it. It has started acting up and would lose power after running for a couple minutes at WOT. It acts like it is starving for fuel. I have drained the gas tank and cleaned it, replaced 10 micron fuel water seperator, replaced filter in front of motor, cleaned VST and screen in it, changed F-filter between primary fuel pumps to vst, injectors have been ultrasonically cleaned. Was put on computer all came back fine no codes. It does not set off alarms. Complete service of the motor, oil change, water pump, thermostat and plugs. Totally lost!!!
Thanks for any advice in advance.

[boats.net]

Try running on a portable gas tank to eliminate boat fuel system. Run fuel pressure test on motor when running and look for a drop in pressure.

I will try it, thanks for the help
I will keep ya posted

Ran the boat on a reserve tank last night, still loses power. Does anybody know anything about the fuel regulator on the VST

[boats.net]

Next step will be to run fuel pressure test.