there are a series of common faults with the 2.0t but they are minor and cheap to fix.
1 is turbo waste gate/control valve, google it for more detail but the link below covers all common faults, they have a little plastic bit in that tares losing boost, only £45 from audi and not too hard to fit other biggie is below:
this is a post i did a while ago
PCV Pressure control valve & bad tickover issues, problems 2.0t
Hi just thought i would post this up here for future problems people might have as all the info i got was off other forums:
So after looking at an american audi forum somthing was mentioned about the PVC, a black thing right on top of the engine which controls gasses flowing around the engine i.e breather etc.
i suspected this could be the fault and when my tickover started to get erratic i decided to get one from audi.
My part number was 06F 129 101 C, after reading i heard a series of people said this had gon to prefix D, then E and we were at G, however when i went to get the part we are now on prefix N!!, was not dear £33 inc vat
Anyway sure enough its all back to normal but i suspect this had been failing for ages apparantly tickover issues is the last straw but poor economy and burning oil also are symptoms & high vacume when you try remove the
oil filler cap when engine running.
Well worth a check for how much its costs!
also the info here is excellent for 2.0T owners, i have replaced all the items mentioned on mine as so far they have all failed/worn i wish i found this when i first got the car as i would have done them all then but the info was harder to come by then!
hope this helps!
http://www.golfmkv.com/forums/showthread.php?t=24952
Both faults seem quite common and seem to go un-noticed unless your quite keen and drive the car hard, but both lead to poor mpg and higher than normal oil consumption so well worth swapping for the cost of them from audi.
Out of interest how much did you pay for yours?
im planning on selling my a4 2.0t quattro avant and not to sure what its worth? has FASH etc but high miles at 130k!