My daughter's 2006 explorer does the same thing. We fill it up, it may go 90 miles or 180 or somewhere in between. The digital "Miles to empty" starts at about 350 full and gradually decreases then just starts dropping quickly; then when the gauge goes below 1/8 tank., low fuel light comes on and there is still plenty of gas in the tank. Turn ignition off or go continuous...no matter. Battery cable off does not reset.
I'm not sure if the pump was replaced before we purchased this vehicle In June of this year. I dropped the fuel tank, checked the resistance on the sender...all good.
So yes, I agree with explorer 2010 that "low fuel light" and "miles to empty" are based on gauge reading rather than actual level of fuel in tank. I have read and read and am just now looking back into it so I can check it out over the holidays when she is here. The issue must be with the gauge and not the sending unit in the tank. I have also seen other threads about anti-slosh module but I'm not sure.
Is there a Ford technician that has seen this same issue?