This is a 1981 240D. The vaccuum pump is producing about 17.5 #'s/in. The doors lock and unlock, the car shuts off, if it has been run for a while. But, it I am just pulling the car into the garage it will take a while to shut off and often, not always, I do not have power brakes when I start out.... and at other times too, but not consistently.

Is this vaccuum pump, brake servo or something else?

How can I diagnosis the problem?

Thanks again and any help would be greatly appreciated.