its none of that as i hhad that prob once. the thorttle body needs resetting, theres a way to do it without the vag, think you need take battery off for 20mins, then connect it then turn ignition on (dont start the car) you will hear a clicking noise i think, after that it should go quiet (dont turn ignition off till the noise has gone) turn ignition off, take key out lock up have a beer or tea or whatever you drink then go back to car and start the car, if it stops doing the reving business then your good if it still carries on then vag com it.
try this (its what i was on about)
[url]http://forums.vwvortex.com/showthread.php?1210265/url] thanks to bored_welsh_lad