[jsb5717]

Do you have an exterior cover on your furnace that you can remove? You might inspect the internals to make sure there are no bug nests blocking internal air/gas flow. It could also be an igniter/flame sensor issue with the gap between the igniter and burner. You can check the needed gap in your manual. Given your symptoms it could also be a buggy thermostat. I believe you can pull the TStat from the wall and just tie the 2 wires together to test the furnace. If it works fine then you know it's the TStat. Or it could also be a faulty main board. I know, lots of options and troubleshooting is difficult.