Americana G.E Range over heating temp set to 350 degrees and range heats up to 500 degrees and burns all food. This model is simple to diagnose the oven temperature switch has the oven probe attached to it. There are no other temperature control parts to go bad. Any time the temperature has large variation you simply need to replace the oven temperature switch. Part # WB20K10026
Start by turning the breaker off and unplugging the range. Remove the switch knob by just pulling forward and unscrew the two Philips screws holding switch to front panel. Next open oven door and locate oven probe sensor (top center). Pinch the two bracket holder and remove from oven wall. Now go to rear of range and remove the back panel. Pull the probe up out of the oven liner hole, don't worry the new one will go back fairly smoothly.
Now its time to install the new switch, remove the wires from old switch one at a time and apply them to the new temperature switch. Be very careful not to confuse what wire gos where. (You may want to write the wire location and colors on a piece of paper first before you start). Put the new switch into it hole and tighten the two screws. Next insert the new probe down in to the oven liner hole. Reattach the bracket to probe and your almost done. Install all covers and its time to cook again.