Sounds like the wiper motor is on its last legs and will probably need replaced. I'm pretty sure half of the Chrysler products in this time frame used the same wiper motor so it shouldn't be hard to find, check somewhere like Amazon before a parts store because you don't need an overpriced, brand name wiper motor for a 20+ year old car. If you give me the exact year I can see if there is a more common issue that could be causing this.