Atwood furnace heating issues?

Casinojunkie wrote:
I have the Atwood hydro flame furnace model #8531-IV 30,000 btu, using a Dometic Duo-therm thermostat.
This furnace has been running very well up until this morning.
Last night, as always, before going to bed I shut the thermostat off.
Upon arising I switched the thermostat to furnace as always.
Furnace within about 5-10 seconds blower started, ran about 10-15 seconds, igniter sparked lighting the burner, as usual.
The burner burned about 3-5 minutes then shut off for about 3-5 min.
did this several times.
Thermostat set for 72* reading was 58*, outside temp was 48*,
thermostat reading would not rise above 64*, turned thermostat to 82* temp inside did climb some but shut off before reaching set temp.
Trying to isolate the problem. Thinking maybe thermostat or limit switch???? Need input for troubleshooting. Thank you

Update!!! This morning I switched on the furnace, temp was 60* inside RV, thermostat set at 80*. Furnace came on as normal, ran continually until 72* was reached and shut off, now it is running intermitly keeping temp at 72* while thermostat still set at 80*. What is your thoughts?