look for the plastic vacuum line to be broke in two- as it passes by the battery enroute to the vacuum reservoir under driver's side fender in front of front wheel-- the battery gases tend to corrode the line-- also look to see if it is plugged in, at manifole, check valve, and at vacuum reservoir. fix it by slipping the right size rubber hose over the two broken ends- no clamps needed.
very, very common problem and fix on your car....