Pontiac Repair: 2000 Sunfire Rear brakes, rear brakes, brake shoes

Question
Hi,
 I have a 2000 sunfire and it is having problems with the rear brakes dragging.  I have personally readjusted the brakes 2 times and had it at a shop twice.  Neither of us can see why they keep dragging.  You can hear it only grabs in certain spots like when the car is moving it makes noise only as the wheel passes a certain spot.  I have changed both the pads and drums and the problem stays the same.  After re adjusting them the problem goes away for a day or so but always comes back. I have also checked the parking brake and its not siezed up.  
Any insite you have on this would be greatly appreciated.
Thanks again
Mark

Answer
Hi Mark:

Did you use good quality brake parts? No cheap brake shoes?? Is this car equipped with ABS? Do you get any ABS lamp on when this happens? Does the ABS enguage before it starts to grab? Do both sides in the rear grab? when it happens does it feel like the rear of the car dips down? It's off that both sides would grab. This car has a diaganol brake system meaning opisite cornes of the cra are linked. The l/f to thr r/r and thr r/f to the l/r So if you had a master cylinder issue here you would have a front brake grabbing as well. If both side in the rear are grabbing I would try another set of shoes try wither Bendix brand or GM Dura-stop. And have a light turn down on the druns. Good luck :)