my 2005 dodge rams 1500 got kick out of overdrive after 70 miles of driving in towing mode

Hi depending on what engine and trany you have and how much weight you are towing... When in T/H mode the trans will shift into top gear (4th or 5th depending on trans model) but the trans shift schedule will be more load sensitive. Trans kickdown shift out of top gear will occur with less throttle opening providing increased engine power....also there my be updates to the PCM (power control Module) that may correct this issue..or your trany could have heated up enough were it didn't want the torque converter to lock up