I had a problem with white smoke coming from my is 220d 2008 model. It was high mileage at 163000. The car gradually started to lose power too when pulling away but suddenly pick up. The garage couldn't find the problem and there were no lights on the dash. Weird?? Any way we decided to look at the turbo. A used turbo is quite cheap so we decided to get one and see if it sorted our problem. The turbo itself is water cooled, unlike a lot of other turbo's and so we think the seals were leaking inside the turbo, hence the white smoke (which smelled sweet like coolant) and this seized up the actuator inside the body and stopped it functioning and hindered the turbo operation. Hopefully its sorted the problem.