E30 Temp Gauge Wierdness
 

My 88 325iC temp gauge has been acting flaky. Before adjusting the valves 2 months ago the needle was steady just below the mid point on the gauge at operating temp. After running the valves the gauge started bouncing, then would level out, then start bouncing again. I cleaned up the corrosion on the injector harness connectors which stopped the bouncing for a few days. It started again but not as bad as the first time and has pretty much settled down for now. 3 days ago the temp gauge popped up to the 1/4 mark when I turned on the key (cold engine). That resulted in temp appearing to run hot. This AM I turned on the key again (cold engine) and the gauge jumped up to the mid point & started climbing from there during warm-up. Disconnecting the temp (thermostat) harness makes no difference in the gauge when the key is in the on position. Anyone have a clue what is happening here?