Taking the truck in tomorrow AM to get it's inspection. I'm towing it up there so as to have have much time for the brakes to lock up. They'll not be driving it too far at the shop, so it should be good before the brakes lock up. Wish me luck.
As an aside, I've now got a theory that there might be a vacuum issue with the motor, which would be causing the vacuum booster to lock up the brakes once the motors been running for a while. Thoughts?