5.7 Litre Power Loss

[dangb]

After two vacation attempts with my 2000 Yukon Denali 5.7 litre the truck had to be trailered home. After approximately 3hrs. of driving the engine begins to loose power. When the accelerator is pressed down the engine balks, back off the accelerator it runs normal. The problem continues to get worse until it will only idle. Strangely after trailering home the vehicle runs normally. Suspecting a fuel problem I recently attached a fuel pressure guage, let the engine idle for 3hrs., drove the vehicle and the problem had returned. When the engine began to loose power I attempted to accelerate and notice the fuel pressure drops to 50psi instead of increasing to 60psi which it usually does when accelerating. When I let up on the accelerator the fuel pressure rises to 55psi and it runs normally. The fuel pump has been replaced 12mo. ago and the fuel filter 6mo. ago. Any ideas? Great around town car but am afraid to take it any distance.

[jro909]

fuel pressure regulator

[ChevyTech77]

Pump.