vac

Oh oh oh I know this one.

Spray some starting fluid around the area you think is leaking. If the car stumbles and idles funny or revs up you have a vaccum leak.

The best bet would be to pull the top intake plenum off and check. That's what I just did and found it around the back side of the intake.

Also I heard like a pissing sound with the engine on. That's a pretty tall tale sign of a vaccum leak.
 
Use a vacuum gauge ($17 at most auto parts stores) to determine if a leak is present. You should see 15"-19" of vacuum at 650-725 RPM.

Use a squirt can of motor oil to squirt around the mating surfaces of the manifold & TB. The oil will be sucked into the leaking area and the engine will speed up. Avoid using flammable substitutes for the oil such as propane or throttle body cleaner. Fire is an excellent hair removal agent and no having eyebrows is not cool...