The best way to deal with this type of problem is to scan the Engine and Electronic Throttle Body Control Computers. There should be some codes that will indicate which component is 'acting up' . Did you have to have your car 'jump started' or get the battery recharged? I ask this because on MB, often times, one needs to re-set all the adaptions if the battery ever goes dead or is replaced. A good independent MB shop should be able to handle this.