+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.
Upcoming NYC dates: Jan 8 and 27. See Facebook for other shows and PM me if you can make one...love to see you there!
Mangofy your E46!