Hi Ray, I agree with Tony I have also had blocked exhausts on these before. But the problem of slight jerking while at cruise has always been cured by replaceing the DPFE sensor (silver box screwed to firewall 2 egr rubber pipes & sensor wires) if we are talking about the same sensor. There is a early & late sensor approx 92-96 & 96> Im sorry but I am at home on holiday as i post this, but if you ring my works number found in members list they can give you the part numbers listed in my tech data folder under Ford, as when I phone my local Ford Dealers they dont have a clue as to what sensor you are talking about. We have cured this problem recently on two mondeos after having tried PCV Valves & throttle potetiometers only the DPFE sensor acheived the cure. Funnily enough we never can get a fault code for this sensor but replacing it does the trick. Good Luck John Kennard.