My oven sometimes doesn't preheat? it will get up to 200 degree and then slowly budge...

it will get up to 200 degree and then slowly budge down.
it works most of the time, but once in a while it will do this
what is it
Can varying the type of furnace be a...
Answers:    Sounds similar to your oven temp sensor is bad. It is supposed regulate the oven temp. but when they move about bad they feat unreliably. Such as yours is doing.
Need counsel on a furnace that I a...