When you unplug the MAF the car runs on stock values loaded in the ECU if you unplug the MAF and the car runs better chances are it's fooked, if you think it runs like poo off a spade unplugged get a new one and it'll be better still.
Do not buy an ebay jobbie MAF or you'll regret it, in my personal opinion get it from VAG, yes it's more but you don't want to gamble on a part like this