bulbs behind speedo fuel gauge flickering on when engine is off no gauges working battery getting drained over night
You might be looking at a failing body control module.
My best guess is power is getting bridged unto the lighting circuit somehow. Possibly by some corrosion taking place. Do you have a trailer hitch with a wire harness that may have some moisture between the terminals. Sometimes this kind of thing can happen to the fuse panels also. Particularly the panel under the hood. Try pulling fuses one at a time in the main panel under the hood to see if you can make the problem stop. You should be able to find which circuit the leak is coming from at least. It would be real helpful to have the factory wiring manual to refer to and help find the problem.