When you had the Carbs off did you check the Float heights were in spec?
Have you checked for Carb seals/Air-leaks?Use a bit of Carb Brake cleaner or WD40 sprayed around them and if the engine speed changes you have introduced a leak.Check that the seals in the Air-box have seated correctly onto the carbs.
Although this is one of my old CX500 pages some of the information is relevant for all CV carbs,
https://cx500.000webhostapp.com/CarbMain.html