WASHINGTON (AP) - Americans regained more of their shrunken wealth last quarter, mainly because the healing economy boosted stock portfolios. But the gain was less than in the previous two quarters. The Federal Reserve reported Thursday that household net worth rose 1.3 percent in the fourth quarter to $54.2 trillion. It marked the third straight quarter of gains. Net worth had risen by a stronger 4.5 percent in the second quarter of 2009 and by an even faster 5.5 percent in the third quarter.