Left rear brake drum gets hot

Ok so I went through and checked the shoes against the backing plate with a straight edge. And it seems to be sitting straight on the backing plate so I don’t suspect a mismatch of parts. I also tested to see whether the front or rear brakes lock up first and the rear brakes don’t actually lock up at all. So at this point I figured it has to be something in the wheel. I swapped the brake shoes around, inspected each spring, even did the drop test, and found no problems there. I assembled everything and drove it. Now the left rear gets up to 407 degrees, and the right rear 286. You could smell the brakes overheating badly. The left front rotor was at 86 degrees and right front at 140 degrees. So it seems like I may have an intermittent issue causing both rear brakes to get hot, and also a consistent issue with the left rear brake running hotter.