Half-ass fixes result in half-ass results; as you now know.
Why didn't you replace the sock filter? (tell the parts store you need one for a 2000'ish Jaguar S-Type, parts system error) It's a $10 filter that is the first line of defense.
Just man up and buy the correct pump new from Ford. It'll save you lots of headaches and redoing work.
Unless you like replacing pumps.