I had a problem with my boxer misfiring.
They are supposed to misfire a little, but it was causing the an alarm to raise on the ECU, I managed to cure it by changing the coil. (changed the leads and it made no difference)
It is always better to start with the cheap parts and work your way up..
When did you last change the plugs ? What type are they NGK platinum ?
I only managed to Get the HT Leads from Alfa Romeo, no one else makes them [img]smilies/frown.gif[/img] £££
They cost more than the coil [img]smilies/eek.gif[/img] [img]smilies/rolleyes.gif[/img] [img]smilies/biggrin.gif[/img]