The U.S. job market no longer looks quite so robust. Employers added a meager 142,000 jobs in September, the government said Friday. And the average job gain for each of the past three months — 167,000 — is well below the 231,000 average for the previous three. All of which renews doubts about a job market in which steady hiring and the consumer spending it drives were expected to fuel continued healthy economic growth. But JPMorgan Chase now estimates that the economy grew at a mere 1.5 percent annual rate in the July-September quarter. The economy occupies a sensitive spot as the Federal Reserve considers whether to raise interest rates for the first time in nearly a decade....