I love my new stove but it's ironic that the reason I shopped for a new stove was because my old stove's temperature started fluctuating and now the new stove's temperature, when set at 350, rises above 400 then drops to about 300 then rises again.  I read two reviews here who said their oven temperature was constant, so I'm wondering why I've been told this is normal. Is it? Please answer.