It’s probably the caliper. I have a 98 and just replaced the rear calipers because they were both bad. If I had to guess, it’s a common issue on these heavy, old, high mileage Acura’s. Make sure you keep the receipt when you buy your new ones and then you can return your old ones and get some money back (if you buy from an auto parts store and do it yourself)

i would recommend replacing both while while you’re at it. If the one is bad, the other one probably isn’t far behind.