Brad, the noise sounds like engine noise to me. You step on the gas, the noise increases, you let off, it decreases. As I said, It happens whether or not the radio is on of off. Kind of like running non-resister plugs back in the day.
Truckernix, the check engine light never comes on. The only lights I see change when it happens is the airbag light comes on and flashes a couple of times immediately after it happens.
Just like when you turn the key on cold before start-up.
