Audi Repair Questions? Ask a Mechanic for Answers ASAP
With the symptom of "feeling like a misfire at low rpm" it sounds like you have a vacuum leak somewhere- which would prevent your wastegate from being activated, since the diaphragm lever is moved by vacuum.
I would guess it is likely your turbo bypass valve, take the little vacuum line of the top of it and apply a hand vacuum and see if it is able to pull an hold vacuum.
And let me know what you find for codes.