Just in case anyone else is having problems with their QE4 when FMQ'ing, this is what seemed to 'cure' my breaking threads and skipped stitches (I was getting about 10 stitches and then mayhem).
* drop feed dogs
*Spring Free Motion (in toolbox)
*Tension-4:6
*90 needle (new)
*Medium speed (press button and use arrows to adjust)
*One-eyed footplate
*Thread in stand up position (will be changing to separate holder when it arrives in the post)
*Pivot height -3 (in toolbox)
*Stitch length to 0
*Open-toed foot
*Auto foot lift to off (in toolbox)
***Re-thread top and bottom (bobbin) after any subsequent breakage
If anyone needs any elaboration on any of the above, please PM me .