The Street couldn’t shrug off government gridlock and doubts about the economy. Stocks, up most of the day, declined in the last half-hour, extending the Dow and S&P 500 losing streak to four days. Investors faced conflicting reports: Home prices rose in July the most in more than seven years, but Americans’ confidence in the economy slipped in September. Investors were also searching for direction following the Fed’s surprise decision to keep its stimulus program fully intact for now. And then there’s the politics in Washington: The US government could shut down soon because lawmakers are making scant progress in budget talks.