The cars engine boggs down when going up a hill. Can put your foot to the floorboard and it slows down even more almost to a stall. this slow down will continue until you get the RPM's between 2500 to 3000 then it will accellerate to as much as needed while on level land. Hit a hill again and boom decelerates again. What could be causing this? Put in a new Fuel filter but want to get a mechanics opinion before playing with the pump or am I in the wrong area all together? HELP!