Miles Thompson had five catches for 147 yards, his second-straight 100-yard game, with an 85-yard touchdown and Robert Tonyan Jr. had eight receptions for 131 yards and two touchdowns for the Sycamores (4-4, 2-3 Missouri Valley).
Indiana State ended a three-game losing streak and handed the Salukis (2-5, 0-4) their fourth-straight loss.
Harker hit Tonyan in the last minute of the first half for a 9-yard score and 10-7 lead. Their 12-yard connection late in the third made it 16-7 and gave him a school record nine this season. He also became the fourth Sycamore receiver to surpass 1,000 yards.
The bomb to Thompson made it 22-7 with 12:34 to play.
Matt DeSomer's second touchdown run with 10:11 left gave the Salukis a shot with the Sycamores missing two field goals and failing to convert on two PATs.