I cleaned the ignition coil(s) last night and painted them with some insulating varnish. The car does feel slightly better, but it's still pinking (but probably not quite as much) and still misfiring. I'm not sure what else I can do now, I'm going to try putting some rubber rings around my plugs (to stop the arcing), but they should work! The sparks go from the top of the plugs (where the ignition lead goes in) and jumps to the metal part at the other end. I can't understand how plugs can do this :-o
It's really annoying now, I think I should probably consider selling it. I could try selling it to those mechanics who told me that there was nothing wrong with it ;-).