Stephen F. Austin (8-4, 5-3 Southland) led by a touchdown when Garrett Atzenweiler broke from the 15 to score, tying the game at 24 with 59 seconds remaining.
Zach Conque promptly drove the Lumberjacks to Northwestern's 23 to set up Wiggs' game-winner. SFA was helped out by pass interference and defensive holding calls, moving the ball to the 33 before Conque's 10-yard run.
Conque threw for 270 yards on 17-of-23 passing and ran for another 71 yards. Gus Johnson, who ran for 161 yards, became SFA's career rushing leader with 3,825 yards.
Conque's 32-yard scoring strike to Tyler Boyd gave the Lumberjacks a 24-14 lead early in the fourth quarter.
Zach Adkins threw for 283 yards to lead Northwestern State (6-6, 4-4).