An interesting way to add some random stuttering behavior to your animation would be to use the temporalWiggle(); expression. I love this expression for adding a touch of randomness to a keyed animation, it can make things look more natural.
This is different from the wiggle() expression in that temporalWiggle() always returns values from the keyframed animation, it only varies the temporal sampling of those values. Where as wiggle() will alter a motion path, temporalWiggle() only alters the speed of the motion on the path (the spatial path is unchanged).
You can think of temporalWiggle() a bit like scratching on a DJ turntable. The turntable moves forward through the song (the keyed animation) but the DJ can slow, speed up or even reverse the song. temporalWiggle() does this in a random sort of way.
temporalWiggle() must have at least 2 arguments:
temporalWiggle(frequency, amplitude)
The frequency is in Hz and the amplitude is in seconds.
temporalWiggle(1, 1) would change the sampling by up to 1 second either forward or backward from the current frame.
I've included a link to a simple video that shows this behavior, the circle in the video has two linear keyframes and the temporalWiggle() expression applied. In this case I am using temporalWiggle(1, framesToTime(10)) which will sample up to 10 frames away from the current time for the returned value.
http://reels.creativecow.net/film/temporal-wiggle
Darby Edelen