Hi mark,
Mine still has similar symptoms to yours sporadically. I get very minor misses on random cylinders.
Seems very common place on these engines.
I changed all my coil packs. This has improved things so I now only get one or two every now and again.
I have/had a very similair thing. Changed coil packs and spark plugs and I was still getting maybe 10 or 11 missfires within a 10 minute window on idle. May I add there were no missfires at all while driving. Only when left for a good 5 mins on idle.
I teracleaned the car and the missfires are virtually away. When missfiring it was mostly on cylinder 1 but would do it occasionally on other cylinders. Leaving the car for 10/15 mins I occasionally still get a cheeky 1. But I notice these cars once tuned do seen to have a slightly lumpy idle. Logged blocks 015, 016