Once again I want to set everyone on the right track about transmission service.If you have serviced your transmission regularily keep doing so just be sure to change the filter not just replace the fluid as many places are inclined to do now.You have a vehicle with over 80K and the trans has never been serviced leave it alone unless there is a problem. Chances are the grit in the fluid is helping the trans perform correctly. On my vehicles I change the fluid in the pan and install a new filter about every 60K a little to liong perhaps but I don’t tow and my vehicles see very little hard use. The other service I do is to add lube gard I may not on the wife’s Rivera but always on my 4X4 Dakota. If you tow be sure to use it I also add a little lube gard to the PS fluid when I change it I only change this when it starts to look dark. I don’t add the full bottle only about half. I change the brake fluid every brake service if it has anti lock if not depending on how it looks. The other services I do areSpray anti mold into the AC heating you will be amazed at the difference in the freshness smellClean the battery terminals every fallReplace antifreeze once a year I only us regular anti freeze never extended life.Clean the throttle body at every tune up.