99 Yukon Intermittent Electric Problem

My Yukon will intermittently loose power to the following all at the same time: ABS Brakes (antilock brake light comes on), Heater Blower, Cruise Control, Transfer Case selector switches. Driving down the road will cause these items to come and go. If they are not working, sometimes shutting off the vehicle and restarting will make them work again. Also noticed that if all appears to be fine, sometimes turning on the heater fan will cause the problem. I think its a bad connection in either the power distribution or ground distribution wiring, but looking at the service manual schematics,
I have yet to find a common point that all these devices share.
Suggestions for tracking this down would be most appreciated. Thanks!