Hi CDB, did you follow M.B.DOC’s suggestion of cleaning the throttle & throttle butterfly? Any results? I did search and found this old thread but my car has same problem and I like to continue the discussion. I have ML320 (2002) with 55K miles. My car idles at 550rpm, a little low, but never stalls. The low idle speed cause the car a little shaking.

M.B.DOC: what liquid that I should use to clean the throttle? Is carburetor cleaning fluid OK? Should I just spray the cleaning liquid and let the fluid flow into the throttle body? Thanks very much for help.