Windshield Wiper Problems?

I have a 1990 Ford Bronco XLT. The windshield wipers recently started having issues. The first 5 to 15 runs the wipers work great. After that, the wipers get jerky and freeze in random places. If I keep the wiper speed on the lowest setting, none of the issues occur. The motors are only a few years old.

How old is the rubber on the blades? Old rubber gets very hard and sticky. The motors are probably drawing more current than the old ones and stalling out.Many have a thermal cutoff when they overheat. The lowest speed uses the least amount of electricity.