Hi, thanks for using JustAnswer.com. Your range is manufactured by Frigidaire. Your model utilizes a hidden element design and by nature these will require more preheat time. The hidden element design is great for keeping the oven clean but, in my opinion, is more trouble than it is worth! Aside from the longer (nearly twice as long) preheat times, it is hard to hold an accurate temperature for "critical foods" that require even temperatures. One thing that may help is to run a clean cycle to burn off anything that may be on the temperature probe that may be keeping it from properly sensing the temperature. You also may want to purchase an oven thermometer to monitor the oven temp and be sure to allow atleast 30 minute preheat time when cooking short term foods requiring little baking time.