Traders work on the floor of the New York Stock Exchange during morning trading in New York City. Michael M. Santiago | Getty ImagesStock futures were muted early Tuesday as investors readied for key corporate earnings releases, including reports from notable tech names.Dow Jones Industrial Average futures slipped 33 points, sitting slightly below flat. S&P 500 and Nasdaq 100 futures were also little changed.Ford Motor slid about 6% after the automaker provided full-year guidance that was..