basic tests for vacum shut off.
1) start it and apply vacum to the shut off, 12 to 15 inchs should kill it, if nit, shut it down and see if it will hold a vacum, if not, replace the element.
2) check the vacum to the shut off element by putting a guage on the line leading to the shut off (as in bypass the shut off) and turning the key to off, it should have 14-17 inchs to the shut off. if not, tap in firther upstrem and check for other leaks. (door locks, dash elements, various devices under the hood.
I've replaced a bunch of the shut offs and a bunch of door lock actuators for leaks causing these not to shut off.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.