So i've managed to finally replicate the issue as well as take a video!
Finally found some time to be able to take it out and run it till empty-ish - about 30 miles left on the tank.
At around 30 miles left i started to feel studdering and rpm lag as you can see in the video. Speed also rising slowly at full throttle. At the beginning of the video you can see the rpms jumping between 2,000 RPM before jumping to 3k rpm and so on.