Mumbai, Sep 6 (PTI) Stocks slipped back into the red today with the Sensex falling almost 148 points to 31,661.97, tracking global sell-off on lingering worries about North Korea and the rupee hitting three-week low against the dollar. The rupee dropped to a low of 64.26 per dollar (intra- day), its weakest level since August 16, on sustained foreign fund outflows despite a weak dollar overseas. After opening lower at 31,713.50, the ...