Thats annoying as hell, its the exact same thing that happened with me though. They should only have to hook up their scan tool read the code, and like i said in my earlier post they then rev it to 4k for 2min, the car shuts down remove key, put key back in, cel gone, drive home. It took them less than 10min, there is no reason they should have needed to keep your car over night. A miss fire isnt really anything major and probably just from the constant starting and stopping while moving your car around the dealer. Sucks to hear your dealer didnt know what they were doing.