But it isn't "always" starting from the same point. Different pumps, different stations, even different temperatures and humidity can cause the actual amount fueled when "topping off" to be more, or less than the time before it. not a drastic amount, but still there.
If the previous suggestions for maintenance don't help. I SERIOUSLY suggest a UIM/LIM teardown and cleaning. you can't mess it up with the HOW-To posted in the Duratec Maintenance FAQ. With more than 33K miles on your engine, you're likely getting pretty dirty. Restore stock horses, and increase your current mileage with this procedure.
Ray
