The stock market took a tumble today, faced with revived upward pressure on world oil prices. The price of oil climbed as pessimism spread about chances for any early resolution of the crisis in the Persian Gulf. Crude oil futures for October delivery jumped about $1.70 a barrel, to well above $31 a barrel, on the New York Mercantile Exchange. In addition, analysts said buyers were holding back awaiting the Labor Department's report Friday morning on the employment situation for August. The figures are expected to show continued weakness in the economy. Speculation has begun to spread on Wall Street that the data might encourage the Federal Reserve to adopt a more stimulative credit policy in an effort to ease strains on the economy and the banking system. But Wall Streeters are not entirely convinced that long-term interest rates would automatically fall in response to such a move. In fact, some say, rates could rise in that setting if fears increased that the Fed was softening its stand against inflation. That, in turn, would stand to leave the central bank in an even worse policy bind than it has to contend with now.