I feel your pain. I just unloaded a glaze firing. The bottom shelf was cone 4 , middle two cone 5, and top cone 6. I can handle cone 5 and 6, I have glazes that I like at each. At cone 4 everything is under fired. My kiln is digital but only has one probe, in the middle. I'm hoping to stack things differently next firing and see if it will even out. I don't know what else to do.
Does a longer soak at the top temperature help to even things out?