[Al Skierkiewicz]

OK,
Here is a test, get the tracks off the floor. put something under the robot to keep the tracks from contacting anything. Then try to drive. If you do not get the same brownout condition, then your robot is telling you that the motors are in stall condition when they are on the floor. Turns will make matters even worse.
If the robot acts the same with the tracks off the floor, you have another issue. We need to see pics inside the robot to get a better idea.