2005 Rio 170k. Car was barely drivable. Sputtering, reving, and stalling. Kia service told me that it needed a short block because the compression was between 120 and 130. I didn't believe that that was causing the problem. I replaced the plugs and wires, same problem. I replaced the coil pack and reset the codes, The car is actually drivable now, about a 90% improvement. But, it still has a slight sputter when accelerating and the Missfire codes came back. It also shutters a bit when at cruise speed on a flat road or downhill. I think I need to look at the rest of the ignition system. Does anyone have a diagram of the whole ignition system and vacuum system. Unless somebody has another suggestion.