Well I've gotten the Mustang back after 5 wks. worth of clutch and flywheel installation. Before the install I was having a problem with bucking and slight hesitation at approx. 1800-2200 rpms through 4th gear at light throttle application. I had my technician check it out and I had coil packs 7 and 4 going bad. Well they have been replaced as well as the spark plugs on all cylinders. On the way to work yesterday it was really bucking and hesitating really bad and the SES light came on. Took it to a reputable shop to have him pull the code. Can't remember what the code was but he stated that it was a right front O2 sensor or MAF meter, vaccuum leak and something else. Anyone have problems like this. Help. My baby is sick.