1972 B-body with 4 wheels drum brakes.

-Completely replaced in 2008. All wheel cylinders, hardware, shoes, lines, hoses, etc.
-No problems the last 2 years. Pulled it out of storage this year and now I have the problem.
-Front brake hoses were leaking at the wheel cylinder this spring. Tightened them and they don't leak anymore.
-I'm running Dot 5 fluid that has turned yellow, but from the info I've found this is normal and not a problem.
-I've bled the front brakes, there was no air in the lines.
-I've adjusted the shoes out so they barely drag on the drums.
-I've switched tires side to side.
-After driving it for a while the problem goes away, then the right side heats up and pulses like a warped rotor.

I've run out of ideas. What else should I check?