Those things are real spooks to figure out, and I sure don't have a definitive answer for you. I had a brand new '88 Chevy Dually once that started doing odd things, like the radio changing stations without my input, the heater changing blower speeds or temps, strange warning lights, and finally, the thing took to quitting running for no apparent reason. Got it towed into the dealer one afternoon, and a mechanic listened to my story, and started laughing; said I needed a replacement brake light switch, that there was a new service bulletin just out on it. With all of the electrics computer controlled, when one component in the system, such as the faulty brake light switch, starts to act up, it can affect any or all of the rest of the systems that are connected through the computer.

Good luck.