[totalloser]

Waste gates are not that erratic. They either work or not. If you have a variable displacement turbo, it could be changing the pitch on the blades or something, but that kind of sounds like the engine may be defueling randomly. Goose it and let off suddenly and see if that sounds the same.

Sure couldn't hurt to check the codes. If it is randomly defueling, OR goofing up the turbo displacement, there are MANY potential causes. If it's the turbo, you'd might burp a big cloud of smoke when it did it, as the air went away.