Temp. Gauge Issue

I'm sorry if I wasn't clear:

Temp gauge moves in a smooth motion from below cold to the cold mark. And when key is turned off and back on the needle moves from below cold to midway in a smooth motion then drops to cold for no reason (of course there is a reason but that is the issue)

The fuel gauges is choppy to a quarter full (ohms read 34 or so) and if it suppose to drop when the key is turned off, it does not.

The resistors are a good idea for sure. I thought by grounding the harness and getting full smooth motion, that the gauges would be good to use (though may be inaccurate). I have also found the circuit boards have had some soldering done to them. Would that maybe give the gauges bad voltage? There are wires soldered from the harness pins to the printed circuit..
I might have better luck wth new/used boards?

Garret