89 t2 electrical problem..?
 

I am considering buying an 89 t2 and when you start the car up its a 14.5 volts and when it warms up it drops to 13.5 . When your driving and you step on the brakes the car seems to almost die and lose power. Is this an electrical problem or engine? New alternator and battery, what can it be? Once you take your foot off the brakes it goes back to 13.5