ummm...
cough and splutter at wot revs ? I get a high rev issue (>7k) if I open up my TC, I found lots of oil in the airbox that when removed it worked OK
till I next gave real exercise and back to square one - my older hex one will rev to the red all day long and has for 35k miles and never had the issue - I'd be happy it was just my TC is crap - except one bod agreed his TC did the same
I was thinking either
1) the engine breather is a joke on the later bike
2) it was owned by a girl that never got the rings to bed in for his 9k miles of use before a grown up got on the thing
3) but - re reading your thread gave me a new thought - does it need thin oil that flows back so the crank doesn't whip it all up and swamp the naff breather - and thus if you run 15w50 weight like the older tractor needs, does this later design whip it up and make a mess in the airbox for riders that use the high top end grunt these later ones were meant to have....
EDIT: Oh your first post you have a real one - not the TC
still point three might apply on TCs
So experience on my older hex... with cold weather rough running. Early ones went better - but ran rougher lower in the rev range. Mid 2008 the early bikes had a range of software mods available that most dealer's ensure they never apply. Three engine points where addressed plus trip computer bugs, side stand logic rethink and TPMS updates - I had the 2008 map flashed on the bike in 2018 - and ever since winter riding has been a hideous mess up. Never an issue in the 8 years prior - but post update winter has been chugging recalcitrant mess up. One of those engine points addressed in the later software was cold weather enrichment...
With the cold back and now using the bike daily - I can't stand the mess - I just bought a new ambient temp sensor (only 12 quid) and some Chinese NOx sensors at 13 quid each - the bike is now dead std with the PC3 out the way and immediately the new CAT sensors show the crazy adaptions waking up and controlling cold weather running much less badly - its still horrific but more rideable - the adaptions per cyl have leveled out - prior cyl one was crazy rich
but extremely light throttle the map is plain wrong - with no fuel to run properly around 2.2k rpm and again at 2.6 to 3.1k rpm - so long as you keep opening the throttle it rides much better and runs well. But idle is weird, its far more stable (without cyl one over fueling), but leave it idling at lights and the thing will go from normal, to chug almost stall, and back to normal 6 seconds later, in a fairly random roughly 90 second batch of confusion. Sometimes it never does it - another ride it will do it every other 10 seconds - the old map was perfect in winter