Windshield Wiper/washer problems of the 2004 Dodge Ram 2500

Improper functioning of windshield wipers. While in intermittent position, they will randomly work at normal low-speeds for a few cycles and revert back to the set speed. Also, from time to time they do not work when the switch is turned on the first time (3 times in 1. 5 years). When switch is turned off then back on they will start to work. Happens more when the wipers are used for long periods. So they can't replicate it, and if they try a tech has to watch continually for hours and because it's a completely random happening, they could well miss it. Basically when you aren't driving the truck for hours in rain looking through/at the wipers you really don't see it. Vehicle has been in 3 times for this issue. First the grounds and contacts were cleaned, to no avail. The 2nd time the wiper control was replaced, which made it happen less often, but still occurs. Third time was today, was told they could not fix the problem because they could not make it happen.