In 1984 Nordstoga was appointed assistant organist at Oslo Cathedral, and from 1994 he has been principal organist.
His repertoire includes a wide range of organ works, the emphasis being on such Classical masters as Bach, Mozart, Franck, Widor, and Messiaen. Between 1990 and 1992 he gave a series of 30 Saturday recitals where large audiences heard him perform all of Bach's organ works, a feat that he repeated within the Bach-year 2000. His concert appearances have also brought him to the majority of European countries.