get it to a dealer/specialist/anyone with vagcom & a laptop and check for fault codes. sounds like a MAF sensor problem to me. If it is the MAF ask the dealership for a refurb'd one and trade in yours, costs about 30% of the new price that way.
If yours is a turbo model there is no dizzy cap but your coilpacks might be on their way out, not a problem if you're still under warranty. VW may even replace them free if you argue long enough (it's a very common fault, a recall took place in the U.S to solve this problem)
