Your 98 doesn't have the endemic problem with the inlet filter of the fuel pump plugging up with hardly any contamination. That didn't happen until part way through the 99 model year when they started using the returnless fuel system.
The fuel intake filter is in the fuel tank. You need to remove the fuel pump from the tank to clean or change it. Unless you have a returnless system it is highly unlikely that you need to do anything with it. If you insist on trying, access is from removing the back seat and removing an access panel.
A weak fuel pump would cause the engine to run very poorly under load (hard acceleration, climbing a hill), especially when the tank is low. This kind of thing would happen long before you would notice any significant drop in fuel economy.
