brake problems

My g/f has a 96 Cavalier and her rear brakes kept locking up and she had no pedal pressure...I replaced all the shoes on the rear and it eliminated the brake locking up. As far as the pedal pressure, I know I'm going to have to bleed the hell out of the system...The only other problem with her brakes is, when she starts coming to a stop and applies brake pressure, the car seems to chug/rock back and forth. Could this be from another problem with the rear brakes or because all 4 need bled? Any help would be great.

Also, one of her bleeder valves is stripped...What is the absolute easiest way to get this thing off without breaking it off? I was thinking penetration oil and/or a torch and usins some channel locks?

Thanks,

Steve

I would also agree with bleeding system. The rocking is probably from warped rotors or out of round drums.
Not to sure about the bleeder valve. I would try the pen oil and channel locks. rusted up, stripped nuts and bolts have caused me to create new swear words.

Ok as far as the rear passenger bleeder valve, it broke off and had to buy a new wheel cylinder from Auto Zone. It was the correct one, but had a small lip on it preventing it from going back in so i had to grind the lip off to fit it in. The steel brake line also broke lol. Had to buy a new one and bend it to fit. Both rear valves will now open/close without a problem...Now I'm on the front passenger side. This valve is locked up good. I tried torching it, spraying it with penetration oil, and nothing. I rounded the bleeder valve out and tried using a socket set for rounded off nut/bolts. Still won't come out. It locked on to it nice and tight, and just when I thought it was breaking loose, the socket was spinning on the bleeder valve. DAMNIT! I was thinking of just doing a ghetto bleed job on it. Just cracking the brake hose loose when someone pushes the brake in, and tightening it back up before they release the pedal. I know this is far from the proper way of doing it, but has anyone tried bleeding like this? I just don't want to break the bleeder valve off like I did on the wheel cylinder. If I did break off the valve, anyone think I'd be able to pull the caliper off, and drill it out and re-tap the hole and stick a new valve in? I don't know how far down I'd have to drill without ruining anything in the caliper...

ok disregard the last post...i finally got all of the bleed valves broken loose earlier...now here's my problem...

I bled the hell out of these brakes. I made 100% sure there was no air in any line. Got it all back together, and the brake pedal go straight to the floor. No pressure at all. What the hell is goin on here? Any help would be great.

Thanks,

Steve