I have a 1988 Mazda RX7... I cant quite figure whats wrong with it, It started out if the cae was in park it will run, but the minute hit the brakes, the car loses all poewer and dies... so I thought it was brake lights, switch, or two sensor and I disconnected them all one at a time and that still doesnt stop it from happening... Now if I rev up the engine it dies, or hit the brakes I get the same response. I have already replaced the altenator.... so thats not it... any suggestions as to what to try next?

 

Plug everything back in you unplugged and then check for vac leaks along the firewall on the brake booster line. That may be causing an issue.

 

Look at a One way check valve. There should be one inside the hose that runs from your brake booster to your main line. Take that hose off and blow through it. You should only be able to blow through it one way.