Have you checked all the hoses? The overbraided vac hoses perish really bad over time and just fall apart, the rest of the rubber hoses aint much better either.

Could be a fucked coilpack?

If the car is DBWS, TBA in vagcom is under engine > meas blocks > block 060 > switch to basic settings for 60 secs... or just pop the bonnet, open the drivers door and turn the ign on. TB will click and whine for a 15-20 secs.