Sounds like you're either referring to the fuel pressure regulator or the Idle Air Control, although neither of these would actually be in line with the fuel lines. The fuel pressure regulator would be connected to the fuel pressure rail.
The fuel filter on a 1989 or a 1998 Taurus would be about the diameter of a pop can and 2/3 as tall. It would probably be located on the passenger side firewall.
-Rod