Ford Repair: 1998 ford ranger, ford ranger, fuel filter

Question
my ranger has 165000 miles  its started not wanting to run good at high speeds . it does ok to bout 70 then it wont go any faster up a hill. just started this lately .. please help thanks .

Answer
could be restrictec fuel filter-catalytic convertor-worn engine especially if running smooth while this is happening
does it run smooth just no power or does it get to running rough
if running rough could be ignition plugs/wires/cap/rotor etc. or a sensor
is check engine light on if it is have it scanned to see if any codes present-follow up  and let me know.