The Vikings (8-8, 3-4 Big Sky) outrebounded the Thunderbirds 35-28. Gary Winston scored 13 points and Andre Winston, Jr. had 11.
Portland State led by eight after a Hall 3-pointer with 12:33 remaining, but Southern Utah crawled back to take a four-point lead.
Following a quick 8-0 run by Portland State, Jeffery hit two jumpers to grab a 64-61 lead with 1:36 left.
Gary Winston hit a layup and Hall drained a 3-pointer to put Portland State on top with 30 seconds left.
Andrew Winston split a pair of free throws after a Trey Kennedy turnover, and Kennedy couldn't connect on a 3-pointer in the final seconds, extending the Thunderbirds' losing streak to 16 games.