Trippir -
how did this end up? I have the same issue with both the temp guage and the oil pressure guage in my 1992 400e. They both work fine - intermittantly and then suddenly jump/drop. The temp jumps to max and the oil drops to the bottom - at the same time. I took the assembly out once and replaces some bulbs, but did not open it or check the wires. I would love to see which wires these two have in common and check them at the connection! Share what you can...I will too.

John