By John S. McClenahen For the second straight month, prices for goods that the U.S. imports from other countries rose in April. The U.S. Labor Department's Import Price Index advanced 1.4%, following a 1.2% rise in March. To no one's surprise, petroleum led the April increase in import prices. Petroleum prices were up 12.1%, only slightly below their 14.5% March increase. In addition to petroleum price increases, a surge in natural gas prices and an increase in prices for chemicals and unfinished metals contributed to the overall rise in import prices last month. Nevertheless, last month the U.S. Import Price Index was 3.9% below its April 2001 level. On the flip side of trade, the U.S. Export Price Index also rose in April, up 0.4% after a 0.3% gain in March. It was the index's biggest one-month gain since Sept. 2000. A rise in prices for U.S. agricultural exports was a major factor, but higher prices for chemicals, petroleum products, paper and metals also figured in the increase. Compared with April 2001, however, the U.S. Export Price Index is down 1.9%.