I've been reading around the site on gas gauge issues, but I'm not sure if mine is the same problem that I have seen.

Recently, every time I get to below a quarter of a tank the gas gauge goes from empty to full,and back and forth while not moving, then when I drive it settles on a third of a tank and slowly crept up toward a half (in reality I had 2 gallons left when I filled it up...)

My truck has been running the best it ever has, is it a simple sensor issue or is this a sign of a future problem with the fuel pump/sending unit?

I have a 2000 btw.

 

Does this post help?

 

It looks helpful....it also looks a little over my head at first glance.

 

More than likely the sending unit in your tank is going south (but not necessarily the pump). Also when the truck is in park you're seeing "real time" readings on your fuel guage, when you're moving it's an average so you don't see fuel slosh while you're driving.