as title,co level is @ 4% and cant adjust it any lower on the potentiometer,i can adjust it richer but not lower than 4%.i took this engine and ecu out of my transit that i had and all was ok in there.it runs ok but there is a slight misfire on full throttle.i've fitted new 071 plugs,decent leads etc aswell as a fse boost valve which is set up spot on.run out of ideas except for changing the ecu which i'll try in the next couple of days.any suggestions?