Idaho was unable to solve Stockton netminder Olivier Roy, who saved 44 shots Saturday.
Trailing by one, Idaho's Tyler Gron tied the game with goal early in the second period, but the Steelheads would not score again.
Late in the second period, Josh Robinson left the crease to defend a Stockton rush, but the puck bounced over his stick as he collided with a teammate and fell to the ice. Stockton's Andrew Clark grabbed the puck and wrapped around the net for an easy goal which proved to be the game-winner.
Robinson had 26 saves in the loss.
How efficient was Roy in the series? Idaho scored just seven times on 191 shots in five games; 96.3 percent save rate.
Stockton managed 13 goals on 155 shots in the series, making Josh Robinson's save percentage 91.6 percent.