Having the stock distributor always makes idle tuning a huge headache. I don't honestly think you will ever have a 100% perfect idle while using it. Add cams to that and it becomes even more difficult!
Usually a hunting idle is due to too much advance at idle. The last 16v I worked on that had a similar configuration idled pretty well, but it was never "rock solid" but it was a race car so it idled a bit high and we never messed with it. It had around 16deg of advance and idled around 13.8-14.2