I know this is probably not going to be something most people come across! >.< But i had loads of trouble with my Harley Quinn corset. When you sew, the foot of the sewing machine gets caught on the PVC and stops moving!
You can buy all sorts of things to sew PVC - the most popular being a teflon sewing machine foot - but there is a cheap and easy alternative!
Simply put a layer of grease-proof paper in between the PVC and the foot. It glides dead easy and all you do then is sew it, then tear the paper off. No mess and no fuss!