my idle drops only when i step on the brake pedal sometime the car even turns off and after couple of crank it starts right back up. any idea where i should look at. this happens with headlights on or off. car idle perfect until i come a stop light or traffic on the highway.

 

If you look at your brake booster, there will be a hose running from it to the intake manifold. On the hose there is a grey plastic valve that is only supposed to open one way. There will be an arrow on it that is supposed to point to the manifold side.

This valve may be defective or installed improperly