Tolliver began his junior year facing Florida State, a game in which he suffered a hairline fracture in his foot, leaving him doubtful for the match. He missed the first three games of the season but returned in Texas Tech's fourth game against Baylor, completing 14 of 25 passes for 189 yards, a touchdown and an interception in a 36–22 loss. Tolliver's next big performance came against TCU, the same team he defeated 63–7 as a freshman. He threw a touchdown pass to Wayne Walker in the last minute to beat TCU 36–35. He finished the season having passed for 1,422 yards and seven touchdowns in eight games. The next season, his senior year, Tolliver and Texas Tech sought to win the Southwest Conference. He started the season strong, throwing an 85-yard pass against Arizona—it was the third-longest pass in school history—but the Red Raiders started with two losses. By the end of the season, Tolliver had set 16 school records and was awarded the Southwest Conference Sportsmanship Award by the league's officials. After four seasons with Texas Tech, he set the school record for career passing yards (6,756), career pass attempts (1,008), career pass completions (493), career touchdown passes (38), season passing yards in 1988 (2,869), and single game passing yards (446) against Oklahoma State University in 1988. Tolliver was inducted into Texas Tech's Hall of Honor in 2002.