I'm having yet another problem with my girlfriend's beetle. I put a new MAF on and it will not go wide open. It just stumbles. And it has a misfire at idle. I put the old one back on and it did the same thing until I unplugged it. Replaced the new one and left it unplugged and the thing ran fine. O2 sensor? Vac leak? It was throwing p0172 and p1128 before the MAF install. I hate this car.