I had that problem for the first 6-months combined with evap system OBD code when the tank would drop down past 1/2 tank. After many trips to dealer (and 1 trip to lawyer ;-) ), turns out hose leading from top of gas tank to evap purge valve was put together wrong closing off the passage. This in-turn also causes another valve to close restricting flow in the filler neck so you can only get about 2-gallons and <click> until the neck can drain down... then another 2-gals... and so on.
Funny thing is... the replacement part comes disassembled and dealership repeated this (pushing the hose too far in the assembly and closing it off) over the course of 6-months of taking the truck back every 2-weeks. While writing a nice check for my troubles, Ford called the service dept. and told them to flip the part over and make sure the hose wasn't shoved in too far before putting the tank back on.