Lately after I start the bike with the choke on, I turn off the choke but the bike is still revving pretty high.

So, I've lubricated the choke cable under the tank but it still gets stuck.

Any suggestions?

May be time to clean your carbs  :mrgreen:

You can try lubing the actual choke mechanisim on the carb.. work it in and out w/ your hand    If spraying the outside w/ carb cleaner, and working doesn't fix it.. You may need to dissassemble and clean the carbs  

Either the choke cable sheath is hangin up: http://gstwins.com/forum/viewtopic.php?t=8782&highlight=choke+cable
Or, the metal bar that pulls both of the choke plungers on each of the carbs is not sliding smoothly.
Or, somewhere the sheath has melted and is preventing the cable from operating smoothly, in which case you may need a new cable.