Welcome. I recently picked up my 84 300SD and do not find it that slow off the line. Just yesterday I got all over a Cat powered bulldozer from a red light. It was close for a few minutes but he finallly reached his top speed and I pulled away.
Well, serioulsy, these do not have great 0-30 times, do they.
Actually, after fuel filter and air filter changes, and driving the car more, the accel. from stop keeps getting better. I have another week off before I start new job so I'll adjust valves maybe on Tuesday. The car had been sitting for some time before I bought it and I am noticing that the more I drive, the smoother the accel. and the tranny shifts get. It takes some getting used to the feel of the accel. pedal compared to my other vehicle. But a good strong push on the MB pedal gets the car moving out pretty well.