each carb has a tiny filter.
is the fuel good?
remove the Raves via the 2 hex bolts on each. they slide out, and remove the small air line. do not disassemble above the engine. remove whole assembly, then take to work bench. (so you don't drop stuff).
slide the metal large clip to the side and pop the cap. make note of how it all goes together. Clean it all out w/degreaser. I use a wire wheel on a bench grinder for the rave slider. and just some simple green or brake cleaner on the rest.
I doubt it's the full cause of your issues, but I clean mine once a season in the fall while winterizing.