MY forced air furnace runs with propane, the other day we had a power outage for 4 days.the fan would not shut off, I then had to replace the heating element, was working fine, then the fan would not shut down, I replaced the thermostat, worked good, and now the fan is running and won't shut down, is there anyone that can assist me in this matter? I really need to get this thing fixed as the wife is sick and I don't need her getting any worse, so please help me anyone

Brand/model #?

The thermostat is a lux and the furnace is a miller

If the furnace has an electronic control board, it may be equipped with a self-diagnostic LED. If so, this will be of great assistance in pinpointing the problem. I'll cross my fingers...