hmm...i dont think the vacuum line has any big significance. i know when i got a short air ram intake, there was a little port for the line to hook up to but on or off it didn't really matter? i'm not 100% sure tho...
about the stall, you might have a bad solenoid. if you stall when the rpms drop, it means that you're not getting enough fuel or the engine isn't combusting properly. it could also be ignition, distributer, spark plugs, etc.
haha sorry for the vague answer