Brakes causing miss and stall?

[MyOldScottsdale23]

I just recently put a crate engine in my 1985 GMC K10 Sierra Classic. It sat for a few months in a field. Since I've had it running when I press the brake pedal all the way I here an air leak under the dash and the engine will miss and stall. Any suggestions?

[bd]

Replace the power brake booster.  Make sure the vacuum hose supplying the booster is in good shape.  The "air leak" is a ruptured diaphragm in the booster.

[Irish_Alley]

[MyOldScottsdale23]

Will do. Thanks. I'll let ya know how it goes.

[Fairlane514]

You may try a new check valve.....its easy and cheap before you have to replace the whole booster.  Its the plastic piece in the front of the booster where the vacuum line plugs into.