so i recently bought a 1990 300zx twin turbo from the auction with rear quarter damage. and it starts right up fine and idles good untill i press the brake it starts to slowly die the more i press it untill it completely shuts down...id be glad to hear all your answers and thanks.

 

Sounds like a dead check valve on the vacuum line to the booster.

 

My guess would be that your alternator isn't charging your battery correctly you should check it ouy