Would you mind giving us a call at 315-299-3589 to discuss this with you.
In the meantime, can you try changing your MAX setting (in the SETUP menu) to something lower. Maybe try reducing it by a third or half.
Also, please make sure the thermostat is mounted on an interior wall, not in the direct path of any vents or drafts, and is not in direct sunlight. If it is sitting on a shelf or couch or something like that "temporarily" it can adversely affect the performance of it.
Also, is it continuously swinging 5 degrees around a steady setpoint, or do you have different setpoint temperatures programmed into it throughout the day? For the moment try using a single setpoint temperature to eliminate setpoint changes from the investigation and troubleshooting.