I have the Pfaff QE4.2. I haven’t a clue how it compares to your model, but I had similar problems when first FMQ’ing.
I now use a 90/14 topstitch needle and aurifil thread. I also only FMQ with a westalee ruler foot, that I invested a lot of time into getting the height and tension correct.
Since then, I rarely have skipped stitches or thread breaks, though I’m admittedly afraid to say that out loud, coz you know, those quilting gods like to laugh at us!