Relooking at this, is it possible that there may also be some play between the sleeve bushing shoulders and the linkage itself. Is there a reason that you went with the 1/16" shoulder on the sleeve bearings instead of the 1/8"? Is there just not enough room to fit them without bending the linkage outward with an extra 1/16" of shoulder on each side?
It seems to me that if the linkage is tight against the sleeve bushing shoulders, and the sleeve ID is 3/8" and the bolt OD is 3/8" that there wouldn't be any play.
Also did you add any lube to the joints? Seems like some http://www.amazon.com/Synthetic-Grease-Syncolon-Purpose-Lubricant/dp/B000XBH9HI would be completely appropriate for the sleeve/metal compression and joint areas. Apologies if I missed that.