Quick guess is: The machine cannot handle the weight of the quilt to feed it under your foot.
Or: You are holding too tight, causing a drag on the quilt that is crippling the machine's ability to feed the fabric through.
A possible solution would be to buy a walking foot for your machine ... a walking foot has a double "foot" on it, with two feet alternately lifting and setting down on the fabric to stabilize the fabric as the quilt is fed through the machine.
I have had problems sometimes with my quilt being so bunched up in my lap, that a crinkle got caught on the table and, needless to say, quilting slowed to a crawl, as my needle is going sixty miles an hour.
To check your control issues (to see if you are being too heavy handed) take a small sample of batting, backing, top fabric and see what your machine does next. Start without your touching it ... then, see what happens when you try to control it in your normal manner. (As a heavy handed machine operator <g> - - us folks with control issues, really do need to lighten up a bit!)
Hope this helps ...
oh! and, if the problem is your machine can't handle the weight, and you don't want to get the added help of a walking foot ... try to figure out some way to make your quilt almost level with the bed of your machine ... keep the quilt as unfolded as possible ...