My Ex Wife owns, an '84 300TD. Almost an identical car as yours. On several occasions she would park the car in the garage, but the engine would not shut-off. it only would happen occasionally.

One day, I found out what was causing it. She would inadvertently, with her elbow, depress the door lock button part way down. Pressing the door lock button only half way creates a vacuum leak and prevents the engine from shutting off. Lowering, or raising the door lock button fully, allowed the engine to shut-off.

Maybe, just maybe your wife is inadvertently also doing the same thing.


Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]