Per Owners Manual
Oven burner will come on immediately and the oven burner will stay on until it reaches the desired setting. Then the oven burner flame will decrease in size. This is normal for this type of thermostat and this flame size will maintain a constant temperature withing the oven. NOTE: Oven thermostat was calibrated at the factory and is not field adjustable.
Sounds like Oven thermostat has failed
2 year warranty from Purchase Date......>//// is you RV buy date past the 2 yrs?
Otherwise......new oven thermostat is roughly $90
Suburban Oven Thermostat 161188