bad miss. The car also is? making a knocking sound in the front. I have had it checked out by a mechanic already. He has put a coil pack on it and done a tune up and changed both the spark plugs and wires. The car is still running the same. He also said that 3 of the 4 cylinders are working properly. He believes the car is getting ready to crack a head gasket. But it has never ran hot. The temperature gage has always stayed in the middle and has never went over but by a little(i'm talking barely over the middle line) and that was when it was sitting still in a taco bell drive thru line for a good while and soon as it did i turned it off and restarted it and the temperature gauge was back to the middle. Somebody please help me. Is my car gonna blow up?