Just thought I would post in case any one else with an auto tranny experiences. When I would slow down to a stop my trans would downshift very hard consistently at 30mph. Although it would not do it with the Overdrive off (OD light on). I took it in to dealer with my suggestion they flash the Powertrain control module (Transmission control module in particular). Guess what ?! the thing operates beautifully now. Not only has the hard downshift disappeared but the acceleration has improved greatly. I always thought my acceleration was on the weak side for being a fuel injected six. Looks like the PCM module just needed tweaking.