Throttle Sticking

[Espo]

I was driving today and my throttle stuck on increasing the engine revs by itself. I turned the engine off and managed to roll into a side street. :

The wierd thing was that the cable was working properly and the spring was returning the throttle linkage to the off position. I played around with it for about 5 mins and on the fourth attempt I started the car and the engine revs stayed at the usual idle.

Is it possible for the butterfly to stay open even when the linkage is returned to the off posi?

I have no idea what could of caused it.

Thanks for any help or ideas?