Bought the car used from a dealer - this is a GM certified vehicle. Noticed the miss almost immediately. Have taken to dealer 4 times now. First time they "could not duplicate", second time they said "normal", third time the fiddle around but no fix, fourth time they cleaned injectors which improved the problem for a week or so but now back to the miss. Very irritating. Everyone who gets in the car notices the miss so it is not just me being too detailed.