By John S. McClenahen For the last few months more than a few economists have wondered if the apparently recovering U.S. economy might lose its forward momentum and fall back into recession. Now there's another prospect -- that the economy might continue its slow and uneven recovery from last year's recession without generating many new jobs. Indeed, according to preliminary data from the U.S. Labor Department, just 39,000 jobs were added to the non-farm sector of the economy during August. That's well below the gain of about 50,000 jobs that many economists had plugged into the recovery models. A source of particular concern is the sharp and unexpected decline in factory jobs last month. Even as services and construction were generating jobs -- up 100,000 and 34,000, respectively -- U.S. manufacturing lost 68,000 jobs, its highest monthly figure since the beginning of this year. For the four months before August, the economy had been shedding factory jobs, but only at an average rate of 18,000, reveal Labor Department data. To further confound the situation, the overall U.S. unemployment rate fell in August to 5.7%, two-tenths of a percentage point below consecutive marks of 5.9% in June and July. Economists generally had expected the jobless rate to rise to 6%.