On A-1 machines interrupted stitching or stitching in place may be caused by a loose machine connector. Please check the ribbon cable connector at the back of the front control panel, then follow the cable all the way to the main circuit board at the back of the machine (you will need to open the cover by removing the screws at the top). Make sure that all the connectors are firmly seated.
If you have a different machine, or this does not work, check all of your IQ connections. You can follow the connections found here: http://intelliquilter.com/iQpedia/Demo_Mode.php
If the problem occurs when the IQ is in manual mode, it may be a machine timing issue and is not related to the Intelliquilter. Also check your needle and around the needle for any areas where it could catch.