My oven seems to run well under the temperature it is set at. In order to get the temperature up to say 375, I have to set the temperature at maybe 550 and then guess as to what the actual temperature is inside the oven.

Is this a bad thermostat?

If you have a solid state thermostat, then you also have a probe on the oven that measures resistance to tell the t-stat what the temp is.

I don't have a chart for your oven as far as the resistance goes. But as my first attempt to repair this, I would change the probe and the t-stat as a pair. Of course, if the t-stat turns out to be a $200 part, then I would probobly start with the probe first.

If you have an old stove with an mechancial thermostat, then you may be able to calibrate it. If not then you can replace it. You will know if your thermostat is mechanical if it has a capilary tube attached to it with a bulb at the end somewhere in the oven.