I have looked all over and can not find the fuel filter in my 2003 expedition with a 5.4.
I just changed mine on my 2000 Navigator today. It was under the driver's side rear passenger door. Up between the fuel tank and frame rail.
I needed a fuel line hose removal tool, and got a shower of gas, lol.
The filter was $10. Ford wanted $75, so told my wife it was my $65 savings shower, so was worth it, lol
Before removing the fuel lines, release the line pressure at the schrader valve on the fuel injector rail. Fuel won't spray out when the line is removed but have a catch pan available to capture the residual fuel in the line and filter.
Start the engine then pull the fuel pump relay or fuse and wait for the engine to die. This will relieve the fuel pressure from the fuel line. Do not reinsert it until you're done installing the new filter or the pump could turn on.