89 F250 wiper issue

I bought this truck about 5mos ago, the wipers worked when first turned on but seemed to get sluggish and slower after a few minutes. So I assumed it was the motor. I took one out of a wrecked 96 F150. My problem is the one from the 89F250 has 2 plugs while the one from the 96 f150 has one plug. I have located wiring diagrams for both but the 150 plug does not have a yellow/red wire and on the digrams it does. Could it be the switch? How do I test it?

I need help guys and would really appreciate any/all replies

Brother...
I hate electrical problems. But at the risk of sounding like an ass, you can purchase a remanufactured (Cardone) from such places as o'reilly auto parts for $50 - $60 bucks. Trying to wire a two to one plug will likely result in more headaches later, especially if the replacement goes south in 5 months.