Stove not pre heating

my 5 year old Kitchenaid Range will not pre heat properly, it heats up to only about 260 Degree in 1/2 Hr. instead of the set 350 Degree Temp. I have performed a " Hard Reboot" with no results. Called Customer Support for some Tech. Advise, the Agent told me to best buy a new Stove. This Stove will pre heat correctly in the Convect Cycle to 350 Degree, but not in the regular Bake Cycle. All other features on this Appliance work fine. Any Advise will be greatly appreciated, Thanks

via Stove not pre heating
by David J. Thompson