It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say. brakes are generally a normal wear item and require maintenance, brake fluid flushed periodically, pads and brake shoes replaced when needed.There are 15 or so bulletins but no recalls on brakes on your car..
Thank you for responding to my question. We been looking into the brake booster. Also found out that the relay( I think that is what it is called) is not working correct at this time. I just got the car and worry it will cost me to much to fix it.