I have a Frigidaire Professional double wall oven with run-away heat in the top oven.
Checked the probes as the first step in diagnostics, they ohmed out OK.
Did some research on several web sites, the issue seemed to center around the Controller being bad. I checked a few appliance web sites and Appliance Parts Pros (APP) was the only one who had the controller in stock and they had the best price by a few dollars. I did the online chat with APP and their conclusion matched my research; the controller was bad. I ordered a new controller and paid for 2 day shipping since I needed the part and didn't have much of a time window to work with. Part arrived on time, I installed it and it did not solve the problem.
I contacted APP through the online chat, the suggestion was to use the link on the specific parts page to have a technician at APP diagnose the problem. Within an hour I received a phone call from APP, the determination was that the main board, not the controller was bad. APP shipped a new board to me via overnight delivery, it arrived the next day, I installed the board and the oven works great.
The service, support and pricing by APP were excellent. I work 7 states away from my residence and get home 4 times per year. I was up against a time deadline and APP got me the parts on time and helped diagnose the problem. Great people to work with, highly recommeded.