On my Frigidaire Dual Fuel Oven, Gas top, Electric oven, it will not heat up, takes 1 hour to get to 200 degrees. No error codes on the display, broil element works fine, Clean cycle works, oven got to 400 degrees when testing with a oven thermometer before I cancelled the Clean cycle. Per other posts I have a feeling that it is the EOC / “Clock/Timer”.
Remove the oven floor. Remove the Bake heating element and check it for continuity. Replace it if the circuit is open.
Check for a broken (burned out) wires.
Check for 240 VAC to the heating element. Replace the ERC (aka a clock) if there is no proper voltage.
Here are the breakdown diagrams and Replacement parts for FRIGIDAIRE PLCS389ECB Frigidaire/gas Range | AppliancePartsPros.com
Gene.
The clock/timer was the problem, replaced the unit last night after ups showed up and it did the trick. 
I’m glad you were able to fix it.
Gene.