You can also try taking your W201 out on an expressway and keep stomping on the throttle and blowing the carbon out that way. Look in your rear view mirror to see the black smoke coming out of your tail pipe. Keep doing it until the black smoke stops. This is what my engineer father used to do with our cars on a regular basis in order to prevent carbon build up from becoming a major problem. After you try this, then take it to be decarboned for $200.