misfire on cylinder 1

[m3csl]

Hi All

I had a cat warning light come on,so I checked the code and it comes up with P0301 (misfire cylinder 1).
So I changed the coil and changed the spark plug,when checking again the same code comes up,so I swapped a plug and coil from a cylinder that I know is working,cleared the code and rechecked,but again the same code...Any ideas chaps.http://forum.a8parts.co.uk/images/smilies/mad.gif