Well, a foot is a bit of an exageration, but he seems to move too far up or down. If it's just a breathing kind of thing, then he'd really only need to move up one pixel and back one pixel.

His height changes because its his idle, not his standing pose. I'll try making it less though.

Wait, since when is 3 pixels a foot? That would mean at his shortest he would be 15 ft 4 in

His height fluctuates by nearly a foot from the looks of it.

Since it's in ZX style, his height should change at all, due to the stance. If it had to move up and down, it'd only be by one pixel, or two at the most.