stumble at low rpm

[rehed]

Hi All,
I have a US 1995 FZR 600 with 6400 showing on the odometer. It starts, idles, and revs good. The issue is that at partial throttle between idle and roughly 2500 rpm it stumbles/feels flat, which makes it tricky to turn left or right from a stop. Above that rpm range it has normal power (power kind of kicks in and stays there). I had synced the carbs last year, spark plugs either last year or the year before, and fuel filter replaced 4 years ago, and it has a K&N filter. I've had the bike for about four years and it's been apart/sitting more than I've ridden it (I use Stabil and Seafoam in the gas), and I think the issue has been there since I got it. I'm trying to sell it now and I've had some beginner riders ask about it, and I wouldn't feel comfortable selling it to a newbie with it's current issue, so I want to fix it. Is there a certain jet that controls that rpm range? Is there another issue that can cause this? Any suggestions would be appreciated.

Steve