If I am understanding you correctly, your concern is the last little bit veers off as you have to let go with your stiletto....one thing I do to control it is the positioning of your left hand/fingers, holding and guiding the piece square to the foot as it passes through, you have to make sure you position your fingers just far enough away so that they don't bump into the foot as it passes under though or you end up with a wobble in your stitching, once I figured this out I had no more veering off!
