+1 on sap. Check both the hose from the pump (for a hole and/or for squishiness) and check that the vac line is intact too.
Also, look in the valve to see if it's clogged from decomposed hose plugging it up. I had this issue...and it caused my car to stall on cold start.
Have you Mangofied your car yet?
Thursday, August 6, 8 p.m. The Comedy Cove--595 Morris Ave. Springfield NJ Reservations: 973 376-3840
Sunday, August 30, 8 p.m. Tierney's Tavern, Montclair, NJ
A recent set.