The problem seems to have come back and gotten worse, only when idling.
When I start my car from cold, it idles at around 1300rpm for a couple of mins, and the engine purrs out of the exhaust, when it gets down to normal idling speed it starts the vibrating, and blowing out the exhaust, (that's what it sounds like).

I've just ordered some new HT leads to see if that will fix it, if not, I'll replace the ignition coil, is there anything else to check?

Cheers.