slight bog when i acclerate.

First of all, i know i have a vacuum leak. there's a metal tube near the intake sensor that has a hose that i have no clue where it leads to. i just found this today. i tried just plugging it, but when i hit the gas the hose swells as it's trying to blow the air somewhere else. don't know how the hose routes. but, any other suggestions as to what it could be besides a vacuum leak?
chris