[DeTomaso] Electrical Gremlins?

[Art Stephens]

    I noticed recently that when I turn on my parking lights,  my temp,  fuel and oil pressure gauges show slight increases in their readings. I would say my temp gauge shows an increase of about 10 degrees.  I would guess that the ammeter would show the same increase if not masked by the added draw from the battery?  Yesterday I developed another problem.  My temp gauge starts dancing around intermittently with the engine running.  It will instantly drop maybe 30 degrees and then jump right back up to the correct temp.  My fuel gauge seems to be doing the same thing.  I took the nut off the ground stud behind the dash.  I removed the wires and cleaned the stud though there wasn't much to clean,  it looked very good.  As I suspected,  no improvement afterward.  With the engine running,  I removed the gauge panel and wiggled all the wires at the back of the four gauges,  I saw no reaction on any of the gauges.  Another quirk,  with the engine shut off,  I turn the headlights on and the oil pressure needle starts climbing past half way.  I don't like having an inconsistent temp gauge and I'm also a little concerned about an electrical fire. I figured the next step I would take would be to check the wire's connection to the water temp sending unit.  Any other suggestions?

Thanks,
Art