Tokyo stocks were slightly lower Monday morning, tracking declines on Wall Street late last week, as caution remained ahead of the two-day U.S. Federal Reserve policy meeting beginning later in the week. The 225-issue Nikkei Stock Average fell 151.15 points, or 0.55 percent, from Friday to 27,371.11. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 10.42 points, or 0.54 percent, at 1,916.76. Decliners were led by securities house, precision instrument, and iron and steel issues.