I'm not sure if they used the same Mikuni carb on the 07 as on the earlier models, but on my 03 and 05 there is an idle adjustment screw under the side of the carb, where the cable enters the carb. If you take off the air cleaner, is the butterfly open at all? It sounds like the throttle isn't closing all the way.
2003Pred; Yoshi RS-3 system, K&N clamp on, Nicolas carb mods,Port&Polished head, Weisco 12.5:1 piston, Nicolas CDI, 14/40 sprockets.
2005 Pred TLD: Quickly becoming the wife's bike.