The Conference Board said Tuesday that its consumer confidence index slipped to 98.7 in June from 103.2 in May, the second straight monthly decline. “Consumers’ grimmer outlook was driven by increasing concerns about inflation, in particular rising gas and food prices,” said Lynn Franco, the Conference Board’s senior director of economic indicators. Consumer prices surged 8.6% in May from a year earlier, faster than April’s year-over-year increase of 8.3%, the Labor Department reported earlier this month. The Fed responded a couple of weeks ago by raising its main borrowing rate by three-quarters of a point, its biggest increase since 1994. The Conference Board’s survey showed that consumers grew more pessimistic about short-term business conditions, the job market and their own short-term financial prospects.