another thing to check would be your intercooler boots, i had a similiar noise with my truck for the longest time and gave up on trying to find it cuse its hard to duplicate in the shop. after about 4 months i noticed it getting louder, then the other day i was towing a heavy load and working the truck hard up a hill and i heard a loud pop! lost power and black smoke like you wouldnt believe pulled over and could hear a whistleing noise in the rf wheel well and looked under the truck to find my lower intercooler boot had ruptured. limped it home, and took it apart. had evidence of a small hole rubbed in it from a hose. fixed it with a new boot and no more whooshing noise. all good now!