In 1990, the Sun Devils opened the season with victories over Baylor University and Colorado State University, but would lose 4 consecutive games, 3 of them while Justin was out with a dislocated left shoulder suffered during a 30–9 loss against the University of Missouri. He also spent two days in a hospital with a probable case of appendicitis, that was later diagnosed as a gastrointestinal problem and caused him to lose 17 pounds. He posted a 4–7 record, 1,876 yards, 10 touchdowns and 10 interceptions.