LG LRE30453ST/01 Heating Issues

I am having oven heating issues with my 9+ year old LG Oven. Several months ago, the oven had an over heating issue in June 2017. This was fixed on a recall from LG and the technician replaced parts 6322B62214A (thermistor) and 6871W1N012B (PWB(PCB) Assy, Sub) lower Relay. The oven worked fine until early December when the oven will not properly heat and has faulted out with F-7 error code. I can get the oven to heat now, but extremely slow, and will not heat past 280 deg. (and this takes +30 minutes). I tested both elements and they are fine. I replaced the lower element just as a precaution and also installed another new oven sensor (thermistor) as the latest one appeared to be bad. I would also note that if I turn on the Broiler, it will not stay on, and shuts itself off. Could the lower control board have failed already? and is there a way I can test it? Or does this seem like it is the main (upper PCB) control board?
Any advice/guidance is appreciated!
One other item...I was able to run a Cleaning cycle.

Shawn

via LG LRE30453ST/01 Heating Issues
by SMCurrie