American Standard Freedom 80 single stage fires up... runs and blows heat for a few minutes then shuts off but then 5 minutes later it repeats the cycle. Any ideas? I have replaced the filter.

A 5 min run time tells me that it is overheating. Probably a dirty evaporator coil, or a loss of airflow due to blower issues. Or even a high temp safety that is opening prematurely? Tstat is calling for heat so its doing its job. It could be overheating or a fault at any of the components in the furnace. 90 percent of the time its a dirty blower wheel, EV. coil, or a missing filter that's so dirty its cutting off the airflow. Hope this helps!

I would take the thermostat off the wall and jumper R&W on the sub base. If the problem goes away its in the thermostat. If the problem is still there it might be time to call a service tech