Another few thoughts.
It may be that the upper thread is not feeding evenly. I assume you are using a good quality thread cover on the cone? (I have found that the soft ones from Superior Threads are really good.) Are you also using a thread stand such as this one by Superior Threads?
https://www.superiorthreads.com/shop...thread-holder/
If you are using the thread stand, you can try folding a small piece of batting and inserting it into the round hole at the top of the thread stand. Your thread then flows not only through that hole, but inside the fold of that batting. Glide is very slippery thread, and that extra bit of tension added by the folded batting smooths out how it feeds to your machine. This is what I have done on my midarm setup, and it does help the thread tension of the Glide stay even as I quilt even when going faster or slower. This might also help keep the thread from jumping out of the tension discs.