I have an 04 G and I have a simular noise on the drivers side of the engine but it sounds more like air escaping or sucking. The car runs fine except it hesitates, and makes a sucking sound when shifting from 2nd to 3rd in automatic mode. It doesn't do it all the time either. I'm old school so I too first thought it was a vacuum issue. Does anyone know of any known vacuum issuse and where I should check?