Former Florida State University President J. Stanley Marshall, who led the university through a turbulent period, died Sunday at his Tallahassee home after a lengthy illness, according to The James Madison Institute, a conservative think tank he founded. He was 91.Marshall was president of Florida State from 1969 to 1976, a time of unrest and protests at universities including Florida State.He went on to found a security business and serve on the Florida Constitution Revision Commission and the state university system’s Board of Governors. He founded The James Madison Institute in 1987.