Hey guys, thanks for the opportunity to join the board. Hopefully i will get and give some good info. So here's my dilemma

99 Suburban 2500 with a 454 bogs down bad while under load while giving it some throttle. It has a strong air sucking sound while it does this. I hooked up a fuel pressure gauge and here are the readings.

Truck cold: ignition on truck not running 50psi and drops down to 22 in 5 minutes
Truck cold: Running at 47psi
Truck cold: 2000 rpms at 47psi
Truck hot: 47psi

No matter what rpm when hot or cold, it stays at 47psi. So i'm thinking its either the fuel pump or the pressure regulator. What do you guys think?