idle+ huge spurts of exhaust gas, 2006 530i

[kiki3]

my car, a 2006 530i, has a rough idle problem. When I stop after driving it, let's say at a traffic light, the idle rpm fluctuates between 600 to 700. I can feel a lot of vibrations on the car seat, and the steering wheel. the car seems to be revving up. Also there is a lot of almost whitish smoke coming out in spurts when the car is stopped at a traffic light. it goes away once i start driving it. i looked around quite a few times to see if the other cars were doing this. very few did so but the exhaust gas was clearer and much lesser than mine. This happens even if I have been driving for more than 20 minutes at speeds of 40 miles and above. i took it to the dealer, he says everything is fine. i don't buy that. i live in Maryland. any suggestions?

[fastshivy]

It sounds like a leak in a vacumn hose. Probably tied to the crankcase ventilation system. White smoke should not be coming out your pipes unless it is water vapor from being cold.I would think water vapor would clear up after 10min of driving. Should be under warranty go back and complain again or find another dealer to look at it.