Issues with squash & stretch script

I've been trying to make a script to apply a "squash & stretch" effect to a movable image, based on the movement - but any time I attempt to do so, the resulting movement comes out jittery and inconsistent. The actual effect takes the form of two parameters - the angle of the stretching, and the magnitude of the stretching. My plan was to calculate the values based on acceleration (such that it would increase:"stretch" when speeding up, and decrease:"sq