It has to be a bad leak or a pump failure to have this kind of an impact. Very rarely will you find it in a single line. There are too many check valves in too many different places to allow one single line to shut your car down like this.

I would say that you have a ripped diaphram in your vacuum pump. Or you have some valves plugged in your pump.

The other perdiciment would be that you have a modulator out at the transmission and a massive leak in your door locks. The modulator would make the car have shifting problems and the major leak probrably coming from the right rear door, trunk or fuel door is causing the shut off and door lock problems.

A simple trick I learned is to, look for the door lock vacuum lines above the brake booster on the driverside firewall. Plug them with golf tees and see if the car shuts off and or shifts better. Then just start eliminating possible problems if symptoms don't change.

Bottom line..... I would suggest pulling the vacuum pump off and putting a rebuild kit in anyway. Next replace the $35 ? somewhere around there modulator, make sure its the right color, and don't use a used one, the one you have is used!

Hope this helps, I have had many many Mercedes with these problems and although their symptoms are always simlair there solutions vary substantially.

Good Luck and happy learning!

Ryan

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Ryan
1985 300D Turbo Diesel
1984 200 Euro