I have the same problem but its very intermittent. Took it to VW to check and they said it was the throttle sensor, funny they didn't find this when it was under warranty?? The throttle body I was quoted at £150. They said the cleaned the throttle housing and it was OK for a while. Looks like I'll be getting a new throttle body when I get paid. What made me laugh is that they said it would take 2 hours to fit and would cost £150 in labour.