The steps i did to test mine were the following, some are optional....
Swap the spark plug from the cylinder misfireing with another, see if fault follows using a scan tool (Vagcom, or other that can detect misfires live)
Swap the coil pack from the cylinder misfireing with another, see if fault follows.
Give it the beans (safely) hit the rev limiter.
Drive a few junctions on the M25 at 5,000 rpm. (it then didn't do it for ages)
I then got the thermostat and HPFP cam follower (as i was not hitting 90 while driving, and the follower had never been changed)
FIX....
She does still have a misfire or two once, maybe twice a week, but nothing like she was....