I have a problem when on the brake pedal like going through a parking lot ri ding them once u let off and reapply they are totaly stiff pedal. Booster or vac pump and how to tell

 

I would first see how much vacuum your pump is generating. Put a vacuum gauge on the small fitting off the booster, or one of the lines that run through the firewall. If it's ready steady at more then 12 inches then I think your pump is fine. Then it might be a booster issue.