2000 Taurus Brake Problems!

Please help! I bought a 00 Taurus that had some passenger side suspension damage (lite wreck). I have replaced all nec. suspension parts and now when I drive it the brakes are very bad. I have to put the pedal to the fire wall to make it stop! I have checked the front and rear brakes, they are fine. All of the lines seem ok. It's almost like I have no power brakes! I'm good with body work and lite suspension work, but brakes and engines are not my fortay! Do they need bled? Could it be the master cylinder? Any help is appreciated!

bad master cylinder is a possibility
Is there a local shop that does free or low cost inspections close to you?