I think I found the solution to the gauge issue, its worked the last three tank fulls.
If I fill the tank to the point when the pump shuts off on its own, then let the foam in the filler neck go down on before putting the cap on, the gas gauge reads full immediately. If I cap it right away, it takes 15 to 18 miles for it to register the full tank.
I have no clue how this affects the gauge unless the float is being hindered by foamed up fuel after a refill?
Pumping fuel slower also seems to prevent the issue but its almost impossible to pump fuel without it foaming up.