I recently had a run-on problem with my '83 300D. Thanks to tips from the forum, I looked and found oil around the vacuum line coming into the shut off valve. With the help of my wife and instructions that I picked up from the forum, I changed out the vacuum shut down valve. After the replacement, I was still having run-on problems. I discovered that the vacuum hose was not sealing in the rubber adapter that fits on the vacuum valve. A good wrap of electrical tape around the vacuum line and the beast runs great now and shuts down every time.

Thanks to all!!

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1983 300D Silver -mine- 185,000 w/ donor transmission
1983 300D Gray (Franklin) -parts car- 180,000- no transmission and no oil pan
1994 S320 Silver -wife's-135,000