Coolant Temp Gauge Issues

[Liberty]

Noticed last night my Coolant Temperature gauge was completely pegged way beyond H. The truck wasn't even hot enough to have the coolant rush into the overflow when I checked the cap, so I know the truck isn't overheating.

Today after a cold start the gauge read Cold as usual before rapidly going up in "temperature" while also wiggling and dancing all over the place.

Its almost acting like there is a short or loose connection, but I'm wondering if maybe it isn't just the sender.