It's paid for and it's reliable. In my book that's a keeper. Spend the money to maintain it, and it will surprise you how many miles you get out of these old Plymouth Sundance models. I think all of them had Japanese engines at the time (maybe Mitsubishi)
I had the same issue with my Isuzu Rodeo. Owned it 23 years and drove it every day as my work vehicle. I maintained it and it took care of me. Finally had to let it go when the rust was just too far in the frame to fix it.