the fuel filter can be found inside the frame rail on the drivers side approximately 4 to 5 feet back from the rear of the front tire. It's a silver metal canister approximately 2¾ inches in length.
remove the fuel pump fuse while you're doing all this (it should be fuse number 19, but check the manual first)
you have to relieve the fuel system pressure, there's a schrader valve on the passenger-side fuel rail (at least it is on the 4.6) hold a rag around the valve as there may be some fuel leakage as it's opened to relieve pressure. to open the valve you have to remove the cap, and use something like a parrallel punch or a pin to push the stem. BE GENTLE. (the valve used here is the same as that used on the wheels for tyre pressure)
don't forget you need to clamp the inlet and outlet lines for the filter, and you'll need a fuel line disconnect tool to release the internal clamps on the fuel lines. this pushes into the filter, around the lines, you'll hear a click when the clamps release. when you've got one line off, plug the opening to prevent the fuel from spilling, do this to the other end when you've taken the whole thing off.
apparently, the best way of removing the filter from the clamp is to push it up, holding the ends and then to "roll" it out of the clamp.
once that's done, fit the new filter (make sure the flow direction is right before you connect the lines) you'll hear a click as the lines lock into the internal clamps. after that, replace the fuse and turn the key to the on position (don't start it yet) doing this primes the fuel pump, pressurising the fuel system. then check for any leaks before you start the truck.
that should be it.
