somtimes when im on the highway ill be in overdrive doing 65 or so and out of nowhere it will downshift one gear. i feels just like i grabbed shifter (automatic) and brought it down to drive. the rps will jack up to about 3000 instead of around 2500 when in OD. i can still give it gas and everything is fine except its in third and not fourth, it might say there for 30 seconds and go back to OD. somtimes it will happen many times in one trip and somtimes it wont happen at all. i dono if its the tranny or some kind of sensor or somthing.