Johnson will be seeking his third Nationwide Tour title on Sunday, and first since it was the Buy.com Tour in 2000. He is also looking to break into the top 25 on the money list -- in position for a bump to the PGA TOUR next season.
'That's what I'll be going for,' said Johnson, who was at 14-under 199 overall.
D.A. Points shot a 3-under 68 and was alone in second place, one stroke behind Johnson at 13-under 200. Kevin Gessino-Kraft also had a 68 and was another shot further back at 201.
Patrick Sheehan fired a 7-under 64 to climb from a tie for 42nd place into a tie for fourth place at 10-under 203. Chad Collins, one of the second-round leaders, and Jason Allred were also at 203.
The tournament was back on track after two weather delays Friday forced the completion of the second round until Saturday. The third round didn't begin until 1:15 Saturday afternoon, with players going off in threesomes from both tees.
Johnson posted birdies on four of his first six holes and made the turn in 32 shots only after stumbling to a bogey at the ninth. He added another birdie at the 13th, then closed with a bogey at the 18th.
This marks the second time Johnson has held a 54-hole lead this season. He shot a final-round 70 and finished tied for third place at the BMW Charity Pro-Am at the Cliffs in May.
It was the second year in a row he held at least a share of the third-round lead at the Cliffs without winning.
'I've had chances to win this year and I haven't yet,' said Johnson. 'I just need to finish one off.'
Jim McGovern shared the second-round lead with Collins, then shot a 74 in the third round to fall into a tie for 11th place at 8-under 205.