I have a 96 civic gsr swap. So sometimes ill be driving around normally and the needle will be sitting normal (slightly below halfway) and then ill look back and the needle will slowly make its way to about 3/4 or a tad bit under 3/4 then go back to its normal position to slightly below halfway. It does that the whole time the car is being driven. The radiator level is fine so is the overflow, no leaks on the floor and there is no moisture where the block meets the head. Car never shuts off nor does it feel weak, when i do pop the hood you do smell a hint of coolant though, but no leaks. I ordered a new radiator cap but otherwise any idea what else it could be?

 

Make sure your coolant system is bled. It sounds like theres an air bubble in your system, causing your temp to spike sporadically.

 

+1 on possible air in the coolant.