My '85 300TD has started acting up - periodically (twice now) it won't shutoff and I have to hit the STOP switch under the hood - I know there's a lot of messages on this topic already, and I understand that it's related to the vacuum system, but - where do I start?!

THx,
James

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K