Several years ago, I was quilting a wall hanging with decorative stitches, using my walking foot and some of the stitches would be fine, but others would be either shortened or elongated, I called my machine guy and he told me that a walking foot was designed to only go forward, so I switched to a regular foot and the stitching was better and not too many stitch problems, since then I don't do decorative stitches as quilting, but give it a try and see what you think.