Hey y'all,
I have an 89 and sometimes it feels like I barely have enough power to come to a stop, and there's alot of hissing coming from the brake pedal. I know that the previous owner replaced the master cylinder, and I bled the lines, and replaced pads. I need some direction on where else the trouble might be and what to do about it. As always, thanks for any help.

 

Sounds like you need a new brake booster. I recently discovered this and its leaking.