is it still running? Shut down, I've learned this past month is controlled by 2 vac lines.
You can trace both to the back of the ignition key. mine are brown with blue tracer- from key to ip rear (shut off side) and the other line is brown-from key to the main vac line (T). If you're lines are connected, possibly something is clogged. Take the second line from the key and connect it directly to the T. You might need to purchase a length of vacuum hose at an auto parts store to do this. If it shuts down, you can plug the other connection where the brown line was previously linked and put another T or Y connection in the mix to locate the brown key line to the same point you made the test connection. If this doesn't work, a tool called mity vac about $60 + at sears, or you can buy it anywhere else and wait for the shipping, is the correct test tool to sort out your vac. leaks. Sometimes the rubber connectors, T's, Y', X's, and inline couplings are the culprit as they tend to dry rot with age and leak.
In an emergency, you can stall out the car by removing the aircleaner and placing a block of wood or NON HOLLOW rubber ball over the intake. Make sure you disconnect the pcv hose on top of the valve cover and block that off or it will continue to run. Starve the intake and the car will stall. BTW, my car as refered to is an 84 240 D, 123 series car. Your's will be different but not vastly.