I'm assuming you X has rear drum brakes, if so, it maybe a matter of doing some manual adjustment to the cam adjuster. The cam is supposed to be self-adjusting if you back up while hitting the brakes, but sometimes rust prevent adjustment. Look at the rear axle flanges for an oblong rubber plug covering the cam adjuster, then remove it. Using a flat tip screw driver, you can adjust it (I'm not sure which direction it needs to be turned) then check the drag by rotating the wheels (on jack stands). You may also want to pull your rotors/drums to check the condition of the parking brake pads...