He now has missed three cuts and finished T-44 and T-72 in two other events in his five starts since mid-March.
Lahiri, whose last sub-par round came on the first day at Texas Open, has not gone below 73 in his next seven rounds.
Meanwhile, the big-hitting Jason Kokrak grabbed a record five-stroke lead through 36 holes ahead of players that include the likes of World No. 1 Dustin Johnson.
But it does not include local favorite Jordan Spieth who missed the cut for the first time at the tournament where he made his debut as a 16-year-old high school junior.
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Kokrak, ranked 128th in the world, shot a bogey-free 8- under 62 for his career-best scoring round and matched the Nelson's 36-hole record at 12-under 128. He is five ahead of Billy Horschel (65), who finished with three consecutive birdies.
Johnson had his second consecutive 67 and was tied for third with Byeong Hun An (bogey-free 66), Bud Cauley (67), Cameron Tringale (68), Jhonttan Vegas (68) and first-round co-leader James Hahn (70).