I have an Ashley 5500xl which runs great for about 10 min. The convection fan comes on and a few minutes later the exhaust fan slows down to about half speed from 116V to about 60Volts. If I shut off the stove and immediately power it back on, it will run at full speed for about 8 minutes then drop the exhaust fan back down to 60Volts. Any ideas if a faulty thermister would do this? I ohmed it to about 1.2million ohms cold and around 80k at operating temp. Any help would be appreciated