JWalker is right. When we hear any water temperature guage-related problems, the board is an immediate suspect. Does pounding on the dash cause the needle to move?

Also, try shining a light through your radiator from the inside out. I have a long-haired cat living in my garage that sheds it's own body weight in hair every week. I have to pull out the radiator and vacuum and hose the cat hair out of my radiator and condenser fins every few years. Bugs can also plug up radiators.