i have this issue currently with my 04.. dash is not the issue its brand new direct from ford.
the sender unit in my tank is shot tapped the signal wires and slowly flilled the tank and the reading were very spurratic at full tank it shows 1/4, half tank shows 1/4, 1/4 shows empty and get low fuel i drive it and it eventually kicks back up to a 1/4 but i dont know exactly whats in the tank... did a system reset and gauge reset.. senders are known to go poof on these trucks from what i see