NEW YORK — King World Prods. Inc. posted Thursday a flat net profit of $35.7 million on flat revenue of $166.8 million for its third quarter ended May 31.The syndicator lately has taken a new lease on life with a new management team, a special dividend to shareholders and by signing Roseanne to a new daily talkshow for fall 1998. The heightened activity hurt earnings in the quarter. The syndie said the new hirings and program development costs ate into operating profits, which fell 5% to $46.6 million in the quarter, but the bottom line was boosted by higher interest income of $8.2 million generated by King World’s enormous cash pile. King World stock fell 18¢ to $34.68. Despite King World’s expanded stock buyback program and its special dividend, the cash pile looms as large as ever. After spending $75 million on the special dividend and $36.2 million on stock repurchases, the syndicator said it had $695 million in cash at the end of May — only $21 million less than the $716 million it reported at the end of the second quarter. Meanwhile, King World said Thursday it promoted 12-year sales veteran Stu Stringfellow from exec VP for domestic sales to president of domestic sales.