1987 Ford F150 302 automatic transmission 5 l 120000 miles.
I replaced my ignition switch on the steering column and mistakenly screwed up the intermittent wiper motor trying to take the knob off of it so I replaced it with a non intermittent wiper motor. I reconnected and grounded it correctly but now I tried to use it and every time the blade goes back and forth it dips the RPMs while idling by about 200 and makes it sound like it is trying to stall. The headlights radio heater or air conditioning do not cause any type of power surge like this. It’s almost as if it is reverse revving the engine. I only got the non intermittent motor because I didn’t have the money to get the intermittent one. I don’t know if replacing it with the OEM motor will fix it or if there’s a way to troubleshoot it. This sort of thing is beyond my knowledge if it is due to faulty wiring.