OSI Restaurant Partners Inc. has agreed to sell controlling interest in its 39-store Cheeseburger in Paradise chain for $2 million to a management group led by Steve Overholt, the unit president. After trying to sell the chain for some time as a noncore asset, OSI will keep an undisclosed stake in the Jimmy Buffet-themed restaurants. Meanwhile, a line of less expensive entrees offered at Outback Steakhouse increased traffic enough to step up promotion and try the idea at the Tampa company's other causal dining chains, according to a quarterly report. The added traffic and $30 million in cost cutting offset the squeeze on first-quarter profit margins from a continuing slump in sales. On Friday, the company reported a 10 percent decline in sales to $964 million for the quarter ended March 31. Operating income used to pay down the privately held company's comparatively high debt rose 9 percent to $109 million. Net income soared to $82 million, up from a loss of $9 million a year ago, thanks to a one-time $158 million gain attributable to OSI buying back $300 million in debt at 30 cents on the dollar.