Jayson Cheesman had eight points and eight rebounds for the Thunderbirds (9-12, 7-5 Big Sky), who won their fourth straight.
Southern Utah never trailed after Heuir tied the score with 15:31 remaining in the first half. Northern Arizona got within 60-54 with 6:42 left, but Stevenett scored five points to push the cushion back to double digits.
There's nothing to suggest the Jayhawks won't end up atop the Big 12 for a 13th season in a row. But what about a return to the Final Four?
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.