Something is wrong with my car's temperature gauge?

The temperate gauge is at a good spot on my car (just below half), where it's supposed to be.

Lately, when I have my car off for about 20 minutes or longer, it drops. It goes way to the bottom as if the dial is broken.

When I turn on my car, it takes a few seconds (as if a car is old) then turns on. Meaning it is stalling as I'm turning the key, to turn the car on for a few seconds

After a few minutes of driving, the dial goes back to its normal spot, just below half.

I don't know why this is happening. Any help?

If it matters: 1999 Honda Civic EX Coupe (2 door)

I'm kind of confused here… Your problem sounds normal to me and not a problem.

When the motors on and running the gauge should go up and be around the middle on most cars. When you turn the car off the engines not running, so it cools off, and the gauge lowers. When you crank it up and drive it, then it climbs back up. Obviously it doesn't heat up instantly, so it will take the gauge a couple minutes to get back to it's 'normal' range.

Your cars working fine. When that gauge quits coming up from the bottom, or goes above halfway, then you need to look into it.

The temperature gauge is behaving normally. It takes time for the water temperature to rise once you start the car.

However, stalling as you turn the key is a different matter. There are a lot of reasons that a car might stall. An obvious place to start looking is manifold pressure (use a pressure gauge). If the pressure is not right, the car might not be tuned right. This might require setting dwell, timing, carburetor idle mixture, etc. Or, it might mean that you have a vacuum leak. It could be something other than a vacuum problem.

It might also be a matter of fixing the choke. Perhaps the choke dashpot has a broken membrane?

There are so many possible causes of this problem, that I think that you need to send your car to a mechanic for a diagnosis.