Original problem was oven took a long time to preheat, then gave an F1 error when cancelling.
Followed troubleshooting procedures and powered up with front membrane panel disconnected and no F1 code.
Ordered replacement panel (P/N AP6010694) and installed, same problem with F1 came back.
Ordered Oven Control Board (P/N AP6010674 - actual P/N WP71001799) and put original front panel in since I assumed it was good. Same problem - took a really long time to heat up to 350 and F1 code came back.
Put the new front panel back in with the new control board and all worked one day.
Then next day turned oven on, won’t preheat and F1 code is back.
Other suggestions anyone?
If you are having problems with oven temperature, I’d suspect the relay board. Did you replace this board
Whirlpool WP74006613 Board, Relay - AppliancePartsPros.com
I found this on a web site, not sure if it applies to yours.
[FONT=Arial Black][SIZE=3]“F1 - Power to Element Relay Energized During Time of Day Display - Check wiring harness and power relay boards for shortages. Replace if defective. Note: For double ovens, replace second oven board.”[/SIZE][/FONT]
Thanks for the reply. Unfortunately that board is no longer available 
another thread suggested the the internal Oven Temperature Sensor (P/N AP4009009