Drove to the side of the road on just about idle. Turned it off and checked for a kink in the fuel line (Fuel line is as short as I can get away with). All good. Started it up again on first kick and it behaved perfect for the rest of the ride. Even when running it hard.
What could be causing this?
(Tank has fresh gas. Plug looks perfect (more towards rich than lean) and throttle response is great. No hanging revs or high idle. Idle is nice and stable)
This is the plug after 30 km. Does not look to lean to me.