Tim have you gotten underneath the dash and looked for frayed wires or anything suspicious? It sounds like a bad ground or something that is shorting depending on the wire harness movement. Problems like this are a real pain to diagnose and are often really frustrating. I'd be looking for wires where they pass thru metal openings, around brackets etc which over the years have worn insulation off the wire. You've got a pretty good sized drain if your battery is dead overnight. While you haven't mentioned it, check your rear door brake light. Sometimes the BOO switch will go intermittently bad which will allow the brake light to be on which will drain a battery quickly (ask how I know..)