The heat in the upper oven will not sustain a set temperature and keeps flunctuating. I am thinking its some sort of sensor or thermostat?? Thanks
Measure the resistance of the oven sensor (#12 in the diagram). It suppose to be about 1100 Ohms at the room temperature. If there is nothing wrong, replace the control board.
Here are the breakdown diagrams and Replacement parts for JENN-AIR JJW8230DDB Walloven - S/c Ele | AppliancePartsPros.com
Gene.