I had a feeling that my problem was the trunk lock diaphragm as that was the first lock to cease working.
The other doors would unlock/lock but the trunk would stay in the locked position.
My first vacuum problem was with a 3 way valve under the hood that went to the cruise control.
I did not have a vacuum pump so I unplugged a line and bypassed it until I located the leak. The leak was in the 3 way valve going to the cruise control.
Good luck,
Chris