That's way too hot. Arizona Mtn. Kings live at high elevations and regularly experience temps in the 50's and lower. They can only tolerate temps of 100 for brief periods of time. Keeping them at 80-100 is like driving a car 60mph in 3rd gear, the snakes metabolism will be running full bore all the time. They need temps at least down into the low 70's on the cool side.
A backround temp that fluctuates between 68-74 with a hot spot of 84-88 is ideal. They also will appreciate a moist hide box.