Hello, I'm looking for some possible causes to a recent intermittent running problem with my Audi a4 cab. Lately when I start the car up it makes a blowing/rattling sound but once the revs settle the noise stops, however the car shakes violently when idling. It has also started to seem.as though its struggling for power and when I reach over 2000rpm it starts sounding very unhealthy. As I said at the beginning its an intermittent problem, some days it will run perfect and others it will seem.as though its about to explode. I wondered at first if it could be the clutch as pulling away can be a struggle and I need to give it a bit more gas than usual but it can pull away in any gear and I can cruise at 30mph in 6th gear with no problem so surely it cant be the clutch?

Sorry to waffle on, any help or advice will be appreciated.