I have found that when I FMQ, if I angle the quilt just a little so that the machine is not sewing straight backwards, but backwards at a slight angle, the stitches look a lot better, and never skip.
Another thing that will make my machine skip is when the spray adhesive gets into a little ball toward the top of the needle..rub that off if it builds up.
Slow down! you may be going too fast...
As the others have said..rethread, new bobbin, new needle...try different thread...sooner or later you'll hit the right combo! Good luck!