In the 2004 season, Burton raced Haas CNC Racing's No. 0 NetZero HiSpeed-sponsored car to three Top 10 finishes but was released from the team with two races left in the season. He spent the next two seasons as a free agent. He returned to the Sprint Cup series late in the 2006 season, driving the No. 4 Lucas Oil-sponsored Chevrolet for Morgan-McClure Motorsports. His first race with the team was the Subway 500 at Martinsville Speedway on October 22, 2006. He started 35th and finished 26th as the last car on the lead lap. On November 5, 2006 at Texas Motor Speedway in his next driving opportunity, he started 37th and finished 25th. On December 12, Burton signed with Morgan-McClure Motorsports to drive the No. 4 car full-time in 2007. That year, his performance was lackluster, posting a best finish of 14th. On November 12, he was released from Morgan-McClure Motorsports so that the team could "evaluate performance." Morgan-McClure closed up shop shortly afterward.