Here's a question for some seasoned 1.8t veterans- all of a sudden by turbo started fluttering when you let off the gas after boost.

I figured it was likely a bad DV, so I took it to Audi for them to check out. Turns out the DV is fine, there are no boost leaks, and no vacuum leaks. They say the turbo spools up to stock PSI.

At this point I'm a bit stumped, and searching the forums hasn't turned up anything definite for me. Any chance it could be a stuck waste gate or n75?
Is there anyway to tell which would be causing a problem?

Thanks in advance for any help!

EDIT: The car currently runs and drives fine, and there are no MILs. The shop I took it to did say that there is a code for a bad ECT-not sure if this is related or not.

 

I am having this problem as well but only if I don't drive the car long enough for it to cool all the way down can you get it to stop by building high boost? When I do that it usually blows what ever is stuck open but it's very annoying and is like to get it fixed any luck?