Check your secondaries
I own the same year & model machine. I bought mine used with about 12K miles on it. My "stumbling" in that rpm range was worse on hot days, less on cool. This problem is particularly irritating on the east coast because it happens right in the middle of the rpm range where traffic will allow cruising on parkways.
I sync'd the throttles and it didn't help much. The last owner made quite a few mods to the bike and one of them was to remove the secondary throttle plates. He must have had the same problem because he changed the sprockets so the bike cruised in the 4-5K rpm range. That made the speedo terribly incorrect and the rear wheel wanted to lock up on downshifts. Happily, the last owner included all the o.e. parts with the bike that he'd removed. I replaced the secondaries and the problem occurs much less than it did. Now that the throttles are back to the way they were designed, I'm going to try syncing again. If that doesn't remove the problem, I suspect that the computer may be getting signals from one of the sensors that are out of spec.
If you solve the problem before me, please post.