did you check your fuel filter? clean the injectors?? Are you using the same gas and octane? same type of driving? I have a 98 SE wih the 3.0 Duratec, and I got about 250-300 per tank doing all highway driving, but get about 160-190 city now that I moved from the country to town when I got divorced. and remember, as the engines get more miles on them, they consume liquids faster.
