P0401 Help

I have an 01 Focus Se sedan. It was surging at about 45mph. I done the Hack #1 and it stops, so I went and purchased a DPFE sensor and it still does it and I get the check engine light. I have no vacuum leaks and applyed vacuum to the EGR and it is good. i also have had the fuel pump recall done. Does anyone have any ideas what might be wrong with it. Does the actuator go bad also does anyone know how to check it. Thanks for any help