Mike Scott shot just 2 of 10 from the floor but was a perfect 8 of 8 at the line, while Jordan Scott was a perfect 6 of 6 from the floor.
Jordan Scott made the final basket of the opening half and the Vandals (9-11, 4-5 Big Sky) trailed 39-38. Idaho opened the second half with seven missed shots, falling behind by 11 until Jordan Scott made a layup, sparking a 16-1 run that put the Vandals in front with 10:44 left to play.
The Bobcats (4-18, 1-9) pulled within three, 68-65, with 2:44 remaining, but back-to-back baskets from Jordan Scott, and Idaho's 8-of-10 shooting at the line in the final minute ended the contest.
Danny Robison led Montana State with 18 points.