You can set the fps by doing this:
Track.Play( clip, 0, 30 ); // third parameter is override fps
and clip is the tk2dSpriteAnimationClip your're dealing with.
If you increase by a number that doesn't divide properly by your framerate, you are undoubtedly going to end up with jerky frames. You should enable vsync, and only ever change by a multiple that works with your framerate.
Eg. if your game framerate = 50 and your animation is 51fps, it will HAVE to drop a frame somewhere for it to play properly.