First off, you're right, stay out of the dealership. They're gonna hang ya! (Over and over again) Better off to struggle on your own, as miserable as it is. Back track the circuits and look for a splice or ground that could be corroded. Also, when it's acting up, perform a "wiggle test" to try and isolate the suspect area of loom. Unfortunately when electrical isn't acting up, it's impossible to diagnose. Keep at it man, you'll get it. Sorry I don't have more.