Tokyo stocks sank Monday morning, with the Nikkei index briefly losing over 3 percent, as the latest U.S. labor report added to uncertainty over the strength of the world’s largest economy. The U.S. dollar strengthened to the upper 142 yen range on buybacks as the nonfarm payrolls report for August, released Friday, blurred the outlook for how much the Federal Reserve might cut interest rates later this month. The 225-issue Nikkei Stock Average fell 778.15 points, or 2.14 percent, from Friday to 35,613.32. The broader Topix index was down 51.78 points, or 1.99 percent, at 2,545.64. At noon, th…