You might be on to something there WR , nice one !!! Since reading your post , have done a bit of digging on youtube and found a guy who describes the symptoms pretty much exactly .
Is it possible that the ignition coils , having been in there for 8 years may have deteriorated further due to letting the bike sit idling for a prolonged period , thus overheating ?
https://www.youtube.com/watch?v=W0HtFSyz6bk