1.8T, 2.0, VR6?????

Thomas

If you don't know the size of engine you have... take a picture of the engine bay and post the picture here.

Thomas

First tell us what engine code/size you have in your vehicle. What faults you have (if you have scanned it) and when the mis-firing occurs. If it occurs first thing in the morning and/or when it's wet out, you'd have a leaking ignition coil and/or ignition wires.