NEW YORK (AP).- The American Folk Art Museum, long plagued by financial problems, is celebrating its 50th anniversary with a new exhibition, renewed optimism for its future and its collection intact. At a preview of a new exhibition celebrating its anniversary Tuesday, museum officials discussed its financial status and projection of its future. The museum in September received a $2 million pledge from a longtime trustee and an additional $1 million commitment from other trustees and supporters, said Monty Blanchard Jr., president of the museum board of trustees. Those pledges gave the museum “significant runway to continue the operations of the museum and built it to new heights of artistic greatness,” Blanchard said. In addition, he said, the museum has received $500,000 from the Ford Foundation. As late as this summer, the board had been in