He has made only one bogey through 54 holes, and he only came seriously close to one on Saturday, saving par from the bunker on the par-3 17th.
"I just felt like I was seeing the line and speed really well", Putnam explained.
"To win two out of three is insane to comprehend", he said. "I was on the outside of a couple of things, and felt like I hadn't been used to being in that situation".
South African native Rory Sabbatini played his first event under the Slovakian flag, and shot a second round 67 to move to five-under overall, nine shots adrift of Kuchar.
"My long game, honestly, didn't feel that great", said Putnam, who closed with a 68.
Kuchar is one shot clear of Putnam, who fired a five-under 65 and four strokes ahead of Stewart Cink and Chez Reavie, who shot 62 and 65 respectively in the Tour's first full-field event of 2019.
He finished at 22-under 258, the third-lowest total in Waialae history behind the PGA Tour record of 253 by Justin Thomas in 2017 and Jimmy Walker's 72-hole score of 257 when he won in 2015.
"It was not at all what I was looking for", Kuchar told the Golf Channel.
Comatose woman gave birth to boy, attorney says
The mother has been living at Hacienda after suffering from a near-drowning incident left her brain damaged over 14 years ago . In 2013, an investigation found that a staff member made "inappropriate, sexual statements " about four clients.
Putnam stayed within striking distance without playing his best.
It was only the second time Kuchar has won twice in the same season.
Kuchar is 2-2 when he has the 54-hole lead going into the final round.
However, Putnam handed back the initiative with a scrappy dropped shot at 14, and Kuchar seized his chance to open up a commanding lead when he holed back-to-back birdie putts from 12 feet at 15 and 16. Just needed to make some better swings. He won the Match Play Championship and the Memorial in 2013. Davis Love III shot 6-under 64 to join DeChambeau, as well as Charles Howell III (6 under) and Marc Leishman (2-under 68).
Super-consistent Marc Leishman is on track for another big US PGA Tour payday but the Sony Open title appears nearly out of reach going into the final round.
"Apparently, I need to go buy a lottery ticket today", Reavie said. "For me, I've never had a cushion like this coming down to the last (hole)".
Australian world No.18 Leishman started the final day seven shots behind leader Kuchar but posted a flawless six-under 64 on the Waialae Country Club course to be a shot further back.
It was a hard day for 11-time PGA Tour champion Spieth, who had four bogeys and just one birdie to be tied for 127th and 12 shots off the pace. He has been to five of the islands, and plans to stay another few weeks after the Sony Open.