Cannot find any info on the given model.

Sounds like one of the elements is burned out.
Most units use both elements during preheat either both on or switching back and forth. Many units also do this when in bake as it provides a more even temperature gradient in the oven.

Still cannot find info on this model.

I re-read your post and I must of had my head up my you know what earlier today or maybe just not enough caffeine.

I would also check the temperature sensor.
Here is some info on it.
http://www.applianceaid.com/elecrange.html
Check out 7, 8, 20 and 21.

Without any info on the unit it is hard to troubleshoot so all I have are a couple comments.
I do not know how you know that the unit is at 350 and just keeps going.
If this is a reading off the units display then it indicates that the sensor is reading the temperature but the control board is not using this reading correctly.
If this is the case then I would suspect the control board as the culprit.

Note: That the temperature sensor is a positive device re: the resistance increases with temperature so if there is a short in it's circuit it will keep power going to the element.
Most units give an error code if the sensor is shorted but yours may not have this feature.

If this is an older unit that does not use a control board but has a mechanical thermostsat then odds are the thermostat is shot.