The problem with the down shifting was a bad thermostat. Noticed the engine was running around 200 to 210. Read from some of the other forums that if the tranny gets hot it will downshift out of overdrive to try and cool itself off, that is exactly what was happening. Just hope it didn't fry anything. Never received a check engine light for overheating, just the 1740.
The deal with the speed sensor makes sense. Will try it out and see what happens.
Thanks.