BS34 Vacuum Diaphragm is shot.

My latest project is a KZ750 L3, I bought this bike back in the spring. It ran like crap in the low range but kicked a$$ from mid range on up. I recently removed the carbs for cleaning. When I put them back in, the idle was erratic and if I moved the throttle, the RPM's would surge to about 4-5000 and not come back down. I tested for air leaks around all the connections and fittings but couldn't find any obvious air leaks. I removed the carbs again and was messing around with the slides. 3 would slowly slide back into the closed position, but 1 would just snap back into position. I removed the top cap on the Carb for cylinder # 2 and found (2) holes where the rubber had deteriorated.
I figure the other 3 diaphragms probably aren't in much better shape than # 2 so I'm going to order a set from that U.K. company nrp-carbs... A set of 4 diaphragms is going to cost about $180.
BS34 carbs are weird. They have butterflies and slides??? How does this setup work differently than other carbs?
Do you think replacing the diaphragms will help resolve the idling problem?

The new slides diaphragms may be necessary but won't affect the idle issue. By the way, ALL constant velocity carburetors, including the BS34 have throttle butterflies. These actuate via the throttle cable to open and change the vacuum in the carb body and cause the slides to rise, like all other CV carbs. The main difference between Mik constant velocity carbs and others is that they have an enrichment circuit for starting the bike rather than a choke butterfly.