hey guys, i have a miss fire when the car is warmed up but as soon as you put it in drive it makes a bumping sound but its not consistent. what could it be i am so lost, i took it to a mechanic he said i had a slight miss fire on cylinders 2,4,7 but the more i thought about it i think its the coil pack. i have new autolight plugs (xp104) but the wires are 6 years old? possible problem? i don't know please help.