Complicating matters was a tense relationship with head coach John McKay and the team's ownership, because of his NFL players' union activities. Stalls ended up renegotiating his contract after the Broncos didn't accept giving up a fourth-round draft choice as part of the trade. He eventually reported to the team and had to pay $40,000 in fines for missing time. On October 18, he was waived after the Buccaneers were notified that he signed a future services contract with the Denver Gold of the United States Football League. On November 10, 1983, needing help on the defensive line, the Los Angeles Raiders signed Stalls to a short-term contract after the Denver Gold agreed to loan him. Although he didn't have the size, he was used as a pass-rushing nose tackle where his quickness created mismatches en route to the Raiders winning Super Bowl XVIII. Stalls took two weeks off after the Super Bowl to physically recover from the grind of the NFL season and joined training camp in February. In 1984, he led the team in sacks with 12.5 (sixth in the league) but his production started to decline halfway through the season because of his body exhaustion. On May 18, he announced his retirement to concentrate in his next career. After sitting out the previous year attending veterinary school at Colorado State University, he was signed by the Los Angeles Raiders as a free agent on July 21, 1985. The team used him again as a pass-rush specialist from the nose tackle position. He was released on October 3. After football, he experienced many careers such as marine biology at California State University, veterinary medical studies at Colorado State University, investment banking at Boettcher & Company and Stern Brothers, sales at MCI Telecommunications, youth advocacy with the Center for the New West, senior management with the City of Denver's Recreation Department, founder & executive director of The Spot (gang youth center), executive director of Aspen Youth Experience, President/CEO of Big Brothers Big Sisters of Colorado, and currently the founder & executive director of the Street Fraternity in Denver, Colorado.