Oven does not keep the same heat as the control is set for,

If your oven temperature keeps dropping and takes too long to heat back up, it could indicate a problem with your oven's heating system. Here are a few things you can check:

1. Check the oven's heating elements: If one of the heating elements in your oven is faulty, it may cause the oven temperature to drop. Turn off the oven, unplug it, and visually inspect the heating elements. If you see any signs of damage, such as cracks or breaks, the element may need to be replaced.
2. Check the oven's thermostat: A faulty thermostat can also cause your oven to drop in temperature. You can use an oven thermometer to test the accuracy of your oven's thermostat. Simply place the thermometer inside the oven, set the oven to a specific temperature, and wait for it to heat up. Check the thermometer to see if it matches the oven's temperature setting. If it doesn't, the thermostat may need to be replaced.
3. Check the oven's door seal: A damaged or worn door seal can cause heat to escape from the oven, which can result in a drop in temperature. Inspect the door seal for any cracks, breaks, or other damage. If you notice any issues, replace the seal.
4. Check the oven's control board: If the above steps do not resolve the issue, it could be a problem with the oven's control board. Consult a professional technician to diagnose and repair the issue.

The temp sensor has failed.

Hello. In most ovens with an electronic control, the temperature is regulated by 2 things--the sensor and the oven control board. The sensor is simply an electrically resistive device that changes resistance as the temperature increases or decreases. It is connected to the main control board by 2 wires(just a "pigtail") and the main board is supposed to be calibrated to adjust properly. Most control boards have a built-in program by which you can adjust the calibration +/- 35 degrees. If your oven is outside that range, and you're sure that the sensor is good, the connections are good, etc., then the oven control board temp control circuit has gone bad. Keep in mind, when you turn on an electronically controlled oven, the first time it heats up is USUALLY hotter by about 50 degrees--this allows the floor, walls, and ceiling to reach proper temperature. This is called the initial spike. In gas ovens, the user must wait approximately 8-10 minutes AFTER the oven beeps to cook anything. In an exposed-element electric oven, the user waits approximately 10-15 minutes after the beep. In the hidden bake element models, waiting 20-25 minutes after the beep is normal!
Also, keep in mind, ovens can have 60 degree temp swings higher and lower(as long as the midpoint is close to the chosen temp) I hope I've helped you!

Your oven sensor has gone bad and telling the control board/thermostat to keep heating. Find the model number on the range and go to a parts distributor like repairclinic.com or apdepot.com and order you sensor. This is an easy repair.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/jason_4570d45317834dd3

There are two possibilities for problems with the range. If it has a "timed bake" setting for the oven then it's possible that the last person who used it neglected to return the setting to the manual mode. In "timed bake" mode, the oven will heat to approx. 160 - 185 degrees, what is called a "keep warm" temp. It will maintain that heat setting regardless of what you set the oven temp control to, as long as you're not in the time frame that it's set to bake. This will make trying to bake anything a very difficult procedure.
The second possibility is that the oven glo coil igniter is cracked and will not heat to the proper temp to allow the electricity to flow through it to the oven gas safety valve to allow it to open and let the gas flow to the burner. These things are ceramic and for some reason crack in normal use. If it has a top broiler, that unit is obviously good. Unfortunately, the igniters are seldom interchangeable. You would need a tech to check the igniter with an ohmmeter.

If the fan is working o/k then the oven element is probably faulty, this should be at the rear of the oven behind a removeabkle cover.
Make sure you have the control set to grill , for grilling

he is right in what he says the heating element is feed from the main control board

Repairing the Oven Setting Control

When the oven setting control malfunctions, the oven won't heat. Here's how to repair an oven setting control:

Step 1: Remove the control knob.

Step 2: Remove the back service panel or the front panel, if necessary. Remove other control knobs as needed to remove the panel. The oven setting control is located directly in back of the control knob and is usually held to the control panel by two screws.

Step 3: Testing the control with a volt-ohm-milliammeter (VOM) is not recommended, because the results will not always be conclusive. If you suspect that the setting control is faulty, the best procedure is to substitute a control that you know is working, or you could simply replace the faulty control with a new one made for the oven.

Step 4: Disconnect the electrical lead wires from the control terminal and lift out the control. Connect the new control the same way the old one was connected.

sounds like a bad bake ignitor(uneven heat,long cook times, long preheat times, perhaps even gas smell while cooking)