Spongy brakes=bad idle

Whats next, I have a 99 century and the brake pedal has just gone spongy, when the car was running in park I pumped the brake pedal a few times, as soon as I did that the idle started going up and down dramatically.
I couldn't find any leaks in the vacuum lines so whats next, the brake booster maybe? Any suggestions would be greatly appreciated. Thanks.

Never mind, I got it. It was missing a hose clamp on the end of the Vacuum line between the booster and the intake. Thanks anyways.