Complex sentence: Rizieq was the head of the FPI from 1998 to 2003, and since 2003 he becomes the Chairman of the board of "Tanfidz" and elected as the "Great Imam" of FPI for life since 2013.
Split into simpler sentences: Rizieq was the head of the FPI from 1998 to 2003, and since 2003 he has become the Chairman of the board of "Tanfidz". He has been elected as the "Great Imam" of FPI for life since 2013.