Today I was in a deep puddle, up to the bottom of my door. I had no issues for the next two hours. On my way home I stopped to give the Jeep a quick wash, including under the hood. On my way home from the car wash the tranny went to 3000 rpm/45 mph and then shift to 3rd. On deceleration, while slowing to stop, there's a hard downshift at 1200 rpm. I've been this deep before with no issues. My diff breather tubes are high enough and the CPU has been wet before, so I suspect it's got to be the tranny. It seems like a stuck valve. Is there something I can do to diagnose and or fix this myself? The tranny was rebuilt about a year ago (it had 180,000 on it).