The Eagles recovered an onside kick in the final minute to hold off a furious rally by the Grizzlies at Washington-Grizzly Stadium.
After Adams found Mario Brown for a 9-yard touchdown last in the third quarter to give Eastern Washington (6-2, 4-0) a 42-17 lead, Montana (6-2, 3-2) rallied to score 20 unanswered points to cut the deficit to 42-37.
Adams finished with a 457 passing yards to go with the six touchdowns, which tied his own school record. The sophomore quarterback also had two interceptions.
Redshirt freshman Cooper Kupp had a career-high 182 receiving yards on 11 catches and two touchdowns.
EWU led 21-17 in the 2nd quarter, before rattling off 21-straight points to build a 42-17 lead. Vernon Adam's 34-yard touchdown pass to Kupp gave the Eagles a 28-17 halftime lead.