Our Carrier 58SS100-BC will keep running after the preset temp is reached on the thermastat while this does not happen all the time it has happened a few times already this season. Came home from work the house was 88 degrees thermastat set to 63 I had to take the doors off the furnace so it would shut down.

The problem could be bad wire between the furnace & thermostat. The thermostat itself could also cause what you are experiencing as could a bad relay on the control board.