85 300D won't turn off
If you Engine shuts off there is a good chance that the Vacuum Shutoff is OK.
The next step I cannot be too helpful with. What people do is they disconnect the Vacuum Hose/s that go to the Door locks and the one that goes to the Climate Control System leaving only the Vacuum Shutoff circuit functioning.
Unforunately I do not know what colored hoses go where.
There is another Vacuum Shutoff Valve on top of the Steering Wheel Lock behind and to the Right of the Instrument Cluster and I think some of it can be seen from down below if the Kick Panel is removed. This is the Valve that moves when you turn the Key and gives the other Shutoff Valve on the Fuel Injection Pump Vacuum.
That Valve can go bad and leak as well as the Hoses that go to it.
A new Valve in that area is about $30
Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf



