Yeah there's 2. One in the vacuum pump to intake hose, and another one in the hose that runs around the back of the engine to the firewall.
I have to say though, if you're stabbing at the brake pedal with the engine idling, it's not unusual for the engine to stutter as it's emptying the servo and heavily loading the intake manifold/vac pump. If you had a genuine air leak, the long and short term fuel trims would be huge and the brake pedal would need a heftier shove than normal.
Can you hear a hissing noise at idle that goes when you press the brake pedal? If yes, the brake servo is f'cked. Quite common and mine's been leaking for years, but haven't got around to changing it.