Idling is not good for the engine. As I have experienced my engine wobbling @ 600 for 10 - 20 secs after warming it up by idling.
Instead I started driving off immediately, and it never wobbled
. But once when I parked my car in cold windy garage at my office the engine got very cold. When I started driving off (not hitting the gas hard), my engine seems like it got misfired and it was making a weird sound and the rpm was dancing between 600 and 400
. I stopped aside and called the BMW.
I stalled the engine for a while and then started it and it was normal.
I am planning to go to the dealer and see if they can help. As I see that it is very common to the BMWs though. But it never happened again.