Did you made the 'look' animation (which do the animation of the body up and down) in low priority?
Let me explain:
Do 20 frames. Start your first frame from max up and last frame max down. in the middle, frame 10, you should make the head/body straight like in the basic look you want him to look like.
No, it not should set to cyclic.
With the same way you did the 'look' animation, you should do the Headside animation. from max left to max right, 20 frames, 10 is straight.
The 'Headside' and 'Headup' and also 'Look' I think should be with low priority. I can send to you my spongebob player model in a milkshape file which I made, so you could see how it works..
Hope I helped and sorry for my bad English