I have a 2004 Mach 1 with a Kenne Bell 2.1. I have had the car for about 6 months and when I get out of the throttle it will stumble some times. I checked the 02 MV and it is all over the place. Cruising at 70 MPH it went from 90 to 700 MV. About every 5 seconds or so the MV drop to 90 and...