Annoying Carb fiddling question

I tore my carbs apart (Rd400D) and cleaned the needle tube… this seems to have cleaned up the mid range quite well. Carbs are clean. New float valves set up right (23mm from gasket)

Still when I give it a fistfull and change gears up, as soon as you pull the clutch in, it revs up. Clutch out revs go back to where they should be… it takes a good 500-800rpm up on clutching.
Also when you give it just a bit of throttle (say 3500 rpm) and you go back to idle, the revs stay at 2000 rpm before slowly going to 1200 rpm. I can’t find any air leaks.

Any hints & Clues as to what to check? My MOT is due on Monday, and I’d like the bike to be spot on.