Does it idle ok?
Mine has an intermittent problem. When suffering from the problem it takes ages for revs to die down, up to 15/20 seconds to return to idle, and jumps between 500rpm/2000rpm when idling. Also has a violent misfire/shudder (like ignition cutoff) around 4300rpm but sometimes gets this at lower (or also higher revs). Very annoying. Car is still drivable bit the idle is very frustrating in traffic, and i'm not really able to rev it up when the symptoms are showing 
Vagcom said something about an intermittent Crank speed sensor fault, cant remember offhand, but it involved unreliable voltage readings. I'm hoping to look at the major underbonnet earths tomorrow and maybe change the sensor if i cant find any bad earths.
Will get back here if i do anything!
nice thread hijack, how about start your own thread and if your to stpid to ignore vag-com fault codes then thats up to you, bad earth isnt going to stop it working, its plugged directly to the ecu. just change it and stop moaning, and your case is nothing like the op's one
mine
Hi all my gti takes long for the revs to come down what could it be?
Thanx.
mine does to, thinks its just some thing to do with the icv,
mine does this if i change gear slowly and when you rev the car it does sit for a fraction of a second, and then drops down, much slowly then other cars ive owned
now unless both mine and your car have the same problem i think its normal. but do tell how long it takes, is it slower then you thought?
could also be due to the heavy flywheel, it does hold on to alot of momentum after you've revved it
