Geo Tracker Vacuum Leak

I just pruchased a 95 Tracker with the 16 valve engine. It seems to have
what I would describe as a vacuum leak (It is a pretty loud leak that
you can hear inside the vehicle) that you hear only when lightly using
the addelator. If you are acceleratoring hard it goes away, if you are
ideling you can't hear it only when lightly pushing on the gas. I can't
duplicate it when the vehicle is parked.

The engine seems to run great with the possible exception being the
engine rpm seems to take awhile to go down and then the tach looks like
it does it in stages dropping to about 1500 prm a hesitation then down
to about 1k rpm then down to idle.

I've checked all the vacuum lines on the top of the engine as well as
the connections from the airbox to the intake.

The sound is almost like the sound when there's no air filter on a
carbarated engine.

Anyone have any ides what the problem might be.

Thanks

Wayne Favre
Bothell, WA