Take it apart and toss the end seals and replace them with a healthy bead of RTV, the Felpro gaskets have a non-stick surface so they should be reusable. Fords are notorious for a leak in that area, most times it's the intake end seals that are the problem. Change the sender while your in there, they are cheap and it would be the best time to change it.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”
— Han Solo