I have a Honeywell thermostat that is model number CT87A-4447 and well I can set it to about 78 and it only reads about 70 in the house. We are freezing! The furnace when it comes on only comes on for maybe a minute the shuts off. The cycle is very short. What should I do to fix this?

It sounds like your furrnace had a problem and not your thermostat.