don't use the walking foot for free motion!! you need to use your darning foot also known as a spring foot. it actually has a spring around the shaft. that helps the needle keep from breaking as you move the quilt.
now the other day i got looping when sewing some squares i'd purchased. i think they had poly in them. i finally gave up after cleaning and rethreading and ended up taking some paper and laying it over my seam and sewed just fine. sort of like paper piecing. just tore off the paper when done. no more loops.!