I have replace my power booster and my break master cylinder and now when i drive my truck down the road and come to a complete stop it sounds like air is coming out from my break peddle. My breaks work just fine. What do y'all think?

 

does it keep hissing or just does it when u mash the pedal down quick? uhm down where the push rod for it comes threw the fire wall u will see like a little rubber washer or something around the rod...and its prolly stuck to it and not sliding back to the front of the little tube all that stuff sits in....lol after u look at it this will make more sence it acts like a O-ring for the push rod on the brake pedal for vaccuum assisted brakes...

 

it hisses when i let off but quits when i push the peddle in. thanks.