Bill
That sounds great low mileage is it a ca car? If not check the body for rust. Check the operation of the sun roof also check electric windows for operation. window motors will get some times stuck from rust on bearing motor from non use. also if oil in air cleaner unhook egr valve it will run much better. Also the paint has been a problem the clear coat will show sign of breaking down usually on cars that sit out in the sun.
I have 2 300sd 81 and 83 the 81 bad paint job clear coat gone but runs strong with 220000 miles the 83 with 175000 good paint job strong runining but with a drivers door that a post jump out and hit. My wife and i just love our 300sds
Well when you check that car out let us know what you find sure sounds good. Also take a picture and post it.
Bill

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94 dodge cummings,86 ford 6.9,75 mbz 240d[ sold], 82 mbz 300sd,83 mbz 300sd