I changed plugs about a month ago to NGK iridiums. While doing the change, I disconnected the coil pack plugs and two plugs on the left front side of cam cover to wipe them out with a dry cloth and reconnected them. About 25 miles later the cel came on. I had the codes read (P0660,P1569) we cleared the codes and the cel still comes on and goes off approx. every week or so. The car runs fine. Any experts on this out there?