Welcome to TFP!
You may just need some weight for your skimmer basket to keep it in place. I had the same problem. The way I fixed it was to create a weight for my skimmer baskets by taking a 3 inch piece of 1/2" PVC pipe, capping and sealing one end, filling the pipe with BB's, and then cap and seal the other end. I then secured the weight to the inside sidewall of the basket with a couple of zip ties. Now when the pump shuts off, the basket (and everything in it) remains in place.