Caloric Range/oven

Hi,

My oven is not working while baking; it turns off and on. The food is not baked or broiled. This never happen before. The ignite turns on and stays on until it reaches the desired temperature. If I select 350 degrees, when it reaches 350 degrees it begins to turn on and off and the food does not cook. What can be the problem?

Thank you in advance for your time.

Model # RTR645 Burners on range top will not ignite but the gas is flowing fine. Are there two separate igniters on each side to control the burners? What is the most commom reason for the burners to not ignite?

Also,
Oven ignites but seems to take longer than it should. Is this signs of igniter replacement also?

Thank you for any assistance.