Whiney sound

I have a 2000 Pontiac Grand Prix that I am fixing up for my son. I am getting a whiny sound that sounds like the power steering pump is going out. But the comes when I push the accelerator down and not when I turn the steering wheel. It's always there but not very loud when idling or on cruise control. Any help would be appreciated. Thanks

i would get or borrow a mechanics stethoscope and place it on the various belt driven items on the engine to try to locate what one is noisy when its revved up and makes the noise. harbor freight makes one that goes for about $4 or your local auto parts store may have one you can rent

I have an 08 grand Prix GXP and the power steering pump has been replaces 3 or 4 times now.