I am not a great authority on this subject and will follow this post to learn more. I can only tell you that I have struggled for years trying to perfect my FMQ. I believe, in my case, that when what you describe happens to me, it is because I am moving my fabric too fast. FMQ is the art of getting your foot pedal speed and your hand movement speed coordinated throughout the process. I just keep practicing. I am finally falling in love with FMQ. Another thing I've noticed, is that when I take closeup photos of my FMQing, it actually looks much better than I believe it is. Also, was told to try a larger needle, 90/14. This didn't help me. Good luck!