1998 Mailbu Rear Brake Problem

So I'm working on this Malibu and the right rear wheel will lock up when I'm on the brakes for a second or two then release, then lock up, then release until the car is stopped. Happens in both drive and reverse. After driving it for a minute or two the problem goes away only to come back a short time later. I adjusted it because it was a little loose, lightly sanded the shoes as well as the inside of the drum and no change. The hardware seemed to be in decent shape. No broken springs or retainers. Any ideas? Thanks in advance!

A wheel cylinder can get worn on high mileage vehicles. You could look at this before buying a new one but will have to bleed the system. Air in the system will cause problems.

I will look at it on Tuesday when I get to the shop. Thanks for the help!

I guess flooring it in reverse and slamming on the brakes solves the problem. Although I adjusted them they still weren't Ok. All good now!