By John S. McClenahen Merrill Lynch & Co. Senior Economist Gerald D. Cohen puts it bluntly: "Pricing power has evaporated." That may be a bit of an overstatement, but the inescapable economic fact is that in November, for the second consecutive month, the U.S. Producer Price Index (PPI) declined. November's fall of 0.6%, which was reported by the U.S. Labor Department's Bureau of Labor Statistics on Dec. 13, followed an even-larger 1.6% drop in October. Contributing to November's PPI decline were a 3.8% decrease in energy prices and a 0.8% decrease in consumer goods. The so-called core PPI, which excludes food and energy, rose 0.2% in November. "A bounce in auto prices . . . as new models were introduced helped to push the core PPI back into positive territory following a very rare 0.5% drop in October," notes Maury Harris, chief U.S. economist at UBS Warburg LLC, New York. But neither higher auto prices nor higher November tobacco prices appear likely to continue against "a weak economic backdrop," says Harris.