When an electric range is first turned on to preheat, both the bake and broil elements cycle to heat it up faster. Is the broil element the only one coming on?

Sounds like an issue with the bake element. Kill the power, pull the bake element out a bit. Make sure the wire terminals aren't touching the back wall. Turn the power back on, turn bake on and use a meter to check for 240vac at the terminals. If you have it, you need a new bake element. If not, repost and we will have a look at the wiring diagram, figure out which leg is dead and where it dies.