Electrical/Wiper Problem
Sounds as though it could be a voltage regulator issue. I used to run the solid state cheapo silver voltage regulator on my Duster and I had many issues of voltage dropping when I tried to run accessories. I have since switched out to the Mopar Race regulator (Blue One) and ever since I did, big difference!!!! No more dim headlights, slow directional signals or slow wipers. This regulator puts out a constant voltage of 13.5 volts and it has made a world of difference.