throttle shaft bushings?

So i think my throttle shaft bushings are worn out. What i have on my kz1000m1 is a popping from cylinders 3&4 that made me go richer than i wanted to get the popping gone. I have sprayed carb cleaner/ether on the manifold to head, the airbox boots, the carb to intake flange, and pilot air/fuel screws, and none of these make the motor race or bog, but when i spray in the throttle shaft area between carbs 3 & 4 it bogs hard. The shaft seals are new as of April on all 4 carbs, replaced while trouble shooting a stumble i was encountering (turns out it was a bad coil). Am i right in thinking that my bushings are worn? I had ro richen both carbs way past 3 turns to get the right side exhaust to quit popping. Is there some form of washer type seal that i need to put in there? I didn't see any when i pulled them apart. Just the white washer seals that go on the outside of carbs 1 & 4. The seals were ordered under a suzuki gs1100g since it also has bs34ss carbs

Never mind. Vacuum sync was the issue. Thanks anyway