Chevrolet Repair: Anti-Lock Brakes, petroleum contamination, abs light

Question
I have a 1998 Monte Carlo that's been having problems with the Anti-Lock Brakes. I've had it worked on 3-4 times before and each of those times the anti-lock brake light came on. This time, the low traction light comes on (it also came on with the anti-lock brake light some of the other times). It only stays on for about 30 seconds or so after the brake jerk. Let me start over by telling you what it's doing now (since I got it fixed the other times). Sometimes, when putting on the brakes, the brakes will jerk (like they're trying to stop---it kind of skids) and the low traction light comes on. It had only done this once and my dad tightened the cord thing that is near the tire in the back (I don't know what it's called--sorry!). I was driving about a week ago and put on my brakes to go around a sharp curve. The brakes grabbed and skidded. I lost control of the car and almost had a wreck (which would include going over a hill into water). The car was swerving all over the road and acted like it wanted to flip. Anyway, I was still able to move the wheel even though I couldn't get the car to stop right away. It felt like an eternity, but it was probably less than a minute when I got back in control of the car. What do you think is wrong with the brakes/anti-lock brakes? If you need more info, just ask me. I may not have explained everything as I should have since I don't know much about cars. Thanks for any help!

Answer
First, don't worry about how many times you ask a question. I actually enjoy them.
Second, Have you had the brake rotors turned and the drums turned. If not, have that done. Replace the pads and/or shoes with new.Check for leaks on the inside of your tires, such as a heavy oil type, but kind of slick. This could make the brakes grab and start to skid. Your ABS light is letting you know that there is a problem with your ABS system.
 With oil or any type of a petroleum contamination on the brakes, the brakes will lock up. Your ABS system has recognized this and can not adjust accordingly. Then your light comes on.
After fixing your pads ,shoes,rotors and drums, you should be able to test your ABS by accelerating to 30-40 and try to come to a controlled stop by pressing on the brake as if you were in a panicky but not agressive stop.
If you feel the pedal starting to push back, your ABS is working.