Can you tell if the thread is breaking, which is a tension issue, or shreading, which is a needle problem? My favorite needle for decorative stitching is a metallic (metallica) needle. the hole is designed to minimize shreading of the delicate metallic thread and works well to keep other threads from shreading as well. I used a top stitch needle for FMQ.
You can also try putting the thread on the spindle so it comes off the spool in the other direction.