My S60 is surging/hunting at idle between 700rpm and 1000rpm. It is more pronounced when the a/c is switched on. I'm thinking Mass Flow sensor. I changed the plugs today with no change in performance. I have an OBDII reader. There are no faults appearing on the message display on the dashboard. The car runs just fine, I can pull 6000rpm through the gears no problem. Any suggestions? Regards Chris.