Hi, I have an issue with an eight year old Frigidaire stove, the oven doesn't keep accurate temperature. I tested the temp sensor and it metered right (1100 ohms between terminals) and metered both elements (oven & broiler) and both were about 40 ohms. We went out and bought an oven thermometer and found that when set to 425 the oven will go to almost 500, then down to 350. When set to 325 it goes to 355. Any suggestions before I spend $140.00 on a new control board?