1992 Mitsubishi Montero dead/sluggish windshield wipers

Other Category problem
1992 Mitsubishi Montero 150000 miles

the windshield wipers on our truck go back and forth between very sluggish, 'skippy', and not working at all. For a while, if you pumped the switch from 'off' to 'high' a few times you could get them going, but now that wont work. We swapped out the motor, and we jumped the car to see if maybe its battery was low, but nothing changed. I saw that you answered a similar problem with 'wiper controle module', but ours doesnt have one, its too old. Any suggestions? Thanks so much--