oven won't hold temperature

Hi. that is strange you still the the f7 error after replacing both the sensor and board. Test both the broil and bake elements to make sure they read good. MAke sure nothing is shorted to ground and that you do not have any burnt or damaged wiring. Make sure you’re not dropping voltage and that your power cord is not loose at the outlet or the terminal block. I have attached a service manual on a similar unit. I could not find your exact model.