Now that your puckers are ripped out, pin the dickens out of them and stitch slowly. Your walking foot will probably take care of it.
I don't understand the concept of starching. I would think that the ironing will flatten or matt the batting. I've starched fabric, but never once the quilt is assembled. I suppose that's what I like about this board. Somewhere, somehow, someone has done something that has worked. :lol: