Any idea what would be causing me to loose fuel pressure as the vehicle warms up?
I have the pressure regulator unplugged. With pressure regulator hooked up, I am 5 psi less that the numbers below. I have installed a new pump, new fuel filter and a new relay. Neither effected my problem. Tank was also very clean inside
When truck is started in the morning, pressure hovers around 40 psi. After 10 minutes of driving we are around 25 psi. Additional driving will get it down in the high teens and you can feel the loss of power whenever below 20.

any ideas?

thanks