ok i got a 99 se sport wit 96,578 miles on it. i just changed the fuel pump complete unit 259$ from ford.. now that got rid of the high rpm hikup that it had under 1/2 tank but now at low rpms when i am just puttin around town, it wants to hesitate a lil bit. now i do got a gas mileage problem now as well 170 mile to a TANK.. i only run 93 or higher in it. before it waz gettin a little over 200 to a HALF tank.. i need help can not aford this gas n e more. what ould the problem be ? thank you