Very low rpms on full throttle. Bike won't move

I own a 2009 Hyosung aquila gv125 and I've been riding it well in the last few months but I recently ran the tank a bit low on fuel and it cut out on me, then when I got it home for some reason it would only stay running if it's on full throttle. And even then it would sound like it's in neutral. I've sprayed carb cleaner into the carb but it's extremely difficult to get to. Any advice?

Take the carb out and clean it thoroughly then install a fuel filter.

What he said and if that doesn't sort it, drain the tank, remove and clean fuel tap and rinse tank out with fresh petrol. Dispose of petrol responsibly!!!

I'm not entirely sure how to get the carb out. The air box on the top of it is shaped around the frame making me wonder how they even got it there in the first place..

Update: carb has been sprayed plenty with carb cleaner. They look clean as a whistle but still gave it a spray with the carb cleaner then reassembled. It's now not started because the batteries dead but it's not even starting on a bump start. Any advice pls?

Did you clean out the tap and jets while you were at it?

It only takes a small bit of crud in a jet or internal passageway to knacker things.