Covington tied a school record with six consecutive made 3-pointers, his only baskets from beyond the arc after missing his first five long-distance tries. The six 3-pointers were a career best.
The Vandals (4-4) were up 42-25 with 18:36 remaining when the Leathernecks went on a 20-0 run to take the lead for good.
The Vandals closed to 74-72 with 1:03 left but Fuller and Covington each made free throws. Idaho's Sekou Wiggs made a 3-pointer with 2 seconds left before Conde's two free throws finished the scoring.