i was so happy the other day when i saw this post. i had just brought my '84 300D turbo home after having the valves adjusted and i noticed the same apparent surging the other guys were referring to. my car developed some serious shaking and i'd tried playing with the rack dampener pin and never had any luck. the non mercedes shop down the street diagnosed the shaking as a lack of compression in one cylinder. (s/p compression test) a post on here told me reliable compression could only be determined if the valves were adjusted correctly. i finally got around to having the valves adjusted at a mercedes friendly shop. NO MORE SHAKING, but the engine surged at idle. yesterday, i turned the rack dampener pin outwards a few turns and presto...no more surging! thanks for the help!!