The brake booster hose to manifold needs a one way valve?? The engine has stalled before and yes the power brakes do go out immediately .

 

Yes. The factory hose has a valve that allows the manifold to pull vacuum from the booster. Vacuum in the booster is what allows you to have power brakes. This valve holds vacuum in the booster when the engine is shut off. Get the OEM hose if you can. Easiest fix. If the factory hose no longer fits, cut the valve out of a booster hose from a salvage yard car and use it in your hose.