It could be your impulse sensor. This is also known as the G28, speed, engine rev or crankshaft sensor. Mine caused a stutter or hesitation around the same revs. The oil filter housing had leaked hot oil over it, causing a fault. It's located just back and down a bit from the housing, with a lead and grey plug connector just by it. Tricky to remove, even once the allen bolt is withdrawn, so the dealer did it. Nothing showed on VCDS by the way. The sensor is 06A906433G, cost £120.78 plus an hours fitting & road test. I did look at getting a new one off Ebay, but the dealer advised not due to lack of warranty on part (Audi give 12 months). Mine still has a small oil leak, not sure where it's coming from!
Let us know how you get on.
Alistair