During Lightfoot's time at Hiwassee, his grades remained fairly poor.[4] He played for the basketball team while enrolled, and even though he did not receive stellar marks in the classroom, they were good enough where he could play for a four-year school. After one year at the junior college, Lightfoot left.[4] Due to NCAA rules, by leaving the two-year school early, he was forced to sit out on what would have been his true sophomore season but still afforded him the ability to retain three years of eligibility.[4] During this one year off, he was determining which school to attend. Larry Eustachy, then-head coach of the Idaho Vandals men's basketball team, had approached Lightfoot during his freshman season at Hiwassee.[2] One of Lightfoot's coaches at Hiwassee became an assistant to Eustachy at Idaho, and after encouragement from several of his junior college teammates who had visited that school and had loved it there, and thus he decided to play at Idaho.[2]
Lightfoot played for the Vandals for three seasons: 1991–92 through 1993–94. During his first year with the team, Idaho finished with an 18–14 (10–6 conference) record.[6] He led the team in scoring with 21.8 points per game, and Sports Illustrated named him their national player of the week on February 17, 1992.[6][7] To earn that honor, he had averaged 33.7 points, 10 rebounds and shot 54% from the field in wins over Southern Utah, Northern Arizona and Nevada.[7] At the end of the season, Lightfoot was named to the All-Big Sky First Team as well as the recipient of its Newcomer of the Year Award.[8]
As a junior in 1992–93 he once again led the Vandals in scoring with his 22.3 points per game average.[6] He set the still-standing single season school record by scoring 715 points en route to leading Idaho to a regular season conference championship.[8] They finished with a 24–8 overall (11–3 conference) record, but did not earn a berth into either the NCAA Tournament nor the National Invitation Tournament.[6] On February 15, 1993, Sports Illustrated named him their national player of the week for a second time, almost exactly one year after his first national honor.[7] He averaged 32.5 points and 16 rebounds in wins over Idaho State and Boise State.[7] Against Boise State, Lightfoot scored a then-school record 44 points.[7] The media recognized Lightfoot's outstanding season and named him the conference player of the year.[4]
In Lightfoot's final season, the Vandals finished with an 18–10 (9–5 conference) record.[6] For the third consecutive season he led the team in scoring, this time with a 25.4 points per game average.[6] On December 21, he scored a still-standing school record 50 points against Gonzaga, including a career-high 8-for-11 shooting performance on three-point field goals.[4][6] He had been in foul trouble early in the game and was forced to sit out for 10 minutes in the first half, so his 50 points came in only 30 minutes of playing time.[2] In addition, his teammates only scored a combined 19 points, and the Vandals lost the game 76 to 69.[4] Lightfoot then repeated as the conference player of the year, joining Montana's Larry Krystkowiak at the only two players to achieve the feat at least twice up until that point.[1] Although the team achieved moderate success that season, they were not good enough to play in any postseason tournaments. Lightfoot's individual success during the year, and over the course of his career at the school, saw him graduate in 1994 as the most decorated player in the university's history and one of the Big Sky Conference's greatest players of all time.[8]
In just a three-year career, Lightfoot scored 2,201 points, which stood as the Big Sky's highest total up until the 2017–18 season when it was broken by Eastern Washington's Bogdan Bliznyuk.[1][3] In each year, he averaged 20+ points per game for a career average of 23.1 – nearly four points per game better than the next closest player at Idaho.[8] He was a three-time first team all-conference selection, two-time conference player of the year, and currently holds 13 different records in the Vandals' record book.[8] Among them are the top three single season scoring averages and four of the top six single game scoring marks.[8] His career scoring record is also more than 500 points greater than the second closest player in school history.[4]
While at Idaho, Lightfoot also excelled in the classroom, which was the opposite of what had been occurring at the high school and junior college levels.[2] He did not miss a single class in his three years and graduated on time.[2] Years later, he had this retrospective on the change: "I was not dumb, just lazy and spoiled. I was put on probation at Idaho and they would have kicked me out of there if I screwed up even once. Basketball was everything to me and it was my out, so I gave it all I had and buckled down in school."[4]