Yeah, it definitely wasn’t the tweaks. I decided being brimful of confidence that I would sling some new plugs in it and change the oil. This was the point where I realised the airbox connection to the RHS carb wasn’t attached and letting in air. Being diligent, I fixed that only to have the bike run terribly again. Long story short, air filter is completely clogged and “fixing” the airbox made it worse. However it did at least lead to finding the actual problem. Had a bit of a wrestle to get that filter out too. So not reassembling the bike air box correctly allowed it to breathe. I feel a little stupid now.