Look at the control board closely both sides for evidence of over heating dark beige/brown spots around any component soldered on that board. If there is chances are a bad board. use a multi meter and trouble shoot...

Checked the entire control board, and there are no obvious signs of wear or overheating. Since sometimes it works fine and other times it doesn't, I also checked for loose wires and didn't find any. In the center back of the oven where two wires come out, there is some blackening of the insulation, probably from the heat of a past self cleaning. Some of the sheathing of the wires that pass by the opening have been browned/blackened, but it looks pretty superficial and does not appear to have compromised the sheathing. I guess I'll start trying to figure out how to test the board. Either that or I'll just roll the dice and replace it.