By John S. McClenahen The U.S. economy is definitely not on the verge of tanking. But the relatively fast growth days of this year's first calendar quarter -- real GDP advanced at a 4.4% annual rate -- now seem even more unlikely to be repeated during the current quarter or in the third and fourth quarters. One indicator: Commerce Department data show that personal consumption expenditures increased only 0.3% in April, the slowest rate so far this year and less than half the 0.7% recorded in December 2003. That statistic is of more than passing interest because consumer spending accounts for about two-thirds of U.S. GDP. Don't be surprised in GDP growth dips below a 4% annual rate in the third quarter and is at a 3.5% rate -- or less -- in the fourth quarter.