toyota truck

What would cause a 94 toyota to idle up and down when you press the brakes.

any help would be grate.

the brake booster has vacuum to it. What exactly is the problem...or is it normal.

well.. it is defently not normal, it just started recently and the only time it does it is when i press the brakes. It idles way up and way down till it is about to go dead.

Your brake booster is going bad, its requires vacuum to operate properly. when you hit the brakes the booster is bleeding the vacuum out instead of maintaining it. There fore the engine it attempting to compensate for the loss of vacuum. replace the booster and youll be ok.

Thanks for the help.