White plugs misfire 1 2 3 4 coming up on computer changed all 4 plugs and coils

Hi, I have got an Octavia vrs mk2 2007 and it has intermittent engine management light on so plugged it into a computer and was coming up as misfire 1,2,3,4 changed all 4 plugs which were white and changed all 4 coils and still have the same issue with misfire 1,2,3,4 when plugged in any ideas of what it might be. Cheers!