I have the predecessor to this machine, the Pfaff Performance 5.2. It sewed beautifully at first. Suddenly I couldn't FMQ on it, nothing but skipped stitches, very jerky trying to move the fabric. I have been FMQing many years, absolutely no problems with basic meandering stitches on my other machines, it was like something was holding the fabric making it very difficult to move smoothly. I examined, looked and looked again at all of my settings, thread, needle, cleaning any lint from the machine, had the machine serviced, etc. Thread cutter either didn't work at all or would only cut the top thread. I was even having trouble with some of the decorative stitches. Finally took it into the shop I bought it from, to see what it was I was doing wrong. Set up the machine, and it worked just fine there. Sales person, who loves Pfaff and knows them in and out, said I wasn't doing anything wrong. Took it back home, a few inches of okay stitching, then nothing but skipped stitches.
Posted on Sewing Pattern Review. Someone there suggested I might try plugging it into a UPS unit (Uninterruptible Power Supply - sort of like a surge protector on steroids - evens out high/low electrical surges/power). I was already using a surge protector, but I went ahead and picked up a UPS unit. I was stunned that it worked. Stitching worked, thread cutter worked. Fast forward several months, once again I started having issues. Again took it into the store, again it worked fine there. My UPS was showing as working (green light). I picked up another one in case it really wasn't working. Still issues. Then I altered my method. I like to start off slow, and I can do that on my other machine. What I found is that does not work as well for the Pfaff machine. A bit more speed works better. Going slow is very jerky. I can get reasonable stitches on the machine, but I don't like the machine. For FMQing at least. It still will not cut the bobbin thread, but only when in FMQing mode. Most of the time I can FMQ on it without all of the skipped stitches, every now and again that is all I get. I live in an older house, so I am sure the problem is largely due to electrical current that is not constant. A small part of it is, I think, altering my method on this machine. I finally decided that I hate FMQing on this machine and I won't be using it for that, which is a shame because that is one of the main reasons I got it. It was sucking all of the joy out of FMQing as I was spending all of my time trying to tweak the settings and alter how I do things. It and I just don't click on that front.
Perhaps a UPS unit might solve your issues. Worth a try if nothing else is working. Are you able to take it back to the shop where you bought it and try it out? It was very eye opening to have the machine work correctly at the shop when it gave me nothing but grief at home. It didn't have the jerkiness at the shop either. Actually it wasn't half bad at the shop. Even when I get it to work right at home, it is still more difficult than at the shop. I think the computer board is very sensitive to slight fluctuations in power. Perhaps someday I will be in a different house that doesn't have older wiring and we can be friends (for FMQing that is).