help temp gauge on cluster not workin

[nstygomez]

so on my 96 civic with a jdm d15b the temp needle on the cluster goes up and down.
If I let the car warm up the temp rises to the middle like a regular car but when I start drivin it the temp drops all the way and when I come to a stop like a red light the temp rises back up. And my car idles so the temp droppin does not help bcus it makes it idle higher lol..
Mayb bcus I have a antifreeze leak I haven't got to fix yet?
Thanks in advanced...

[Cynical 1]

low coolant not touching the temp sensor, or a bad temp sensor.

there is a test procedure if you google it...