Fuel gauge problem

[firepop5]

96 explorer, 5.0 V8

Fuel gauge moves up and down while driving. It moves erratically sometimes indicating more fuel than is present, sometimes indicating less fuel than is present. The check gauge light also comes on and off. I would think there is a problem with the float level/sending unit in the tank.
At the same time the message center in the console tells me how many miles until empty. This amount of miles goes down consistently as gas is used, it does not bounce up and down like the gauge does. If the message center reading is also controlled by the float level in the tank, than what is causing the gauge to read erratically?

 

[E-rock]

when you accelerate, your pushing more gas into the engine and the mpg is basically a mathmatical equation in your computer. on a hard acceleration the current avg. mpg will decrease signifigantly. for instance pushing the pedal to the floor in a dodge durango (avg 16 mpg) will cause the screen to say you only are getting 6 or 7 mpg. just the same if you are idling it will say either 99mpg or nothing at all. i dont know if the gas tank gauge is also tied into this but i know mine isnt very linear and fluctuates often. if you are driving at a constant speed and this is happening, then ignore everything ive said because i dont know.