super high idle

1997 GSF 600. When I start the bike it immediately goes to 6000 rpm and won't come down. The throttle cables are working correctly. I pulled the carbs and checked that the throttle plates are closing and they seem to be, put the carbs back on and have the same problem. The boots are kind of hard but would that make it do this. Seems like it might have a massive vacuum leak somewhere but I can't find it, or maybe it's something I'm not thinking about. Any thoughts would be appreciated!