CINCINNATI — Even in a lineup that continues to produce at respectable levels, Michael Conforto’s September swoon screams to the Mets.

A roller-coaster season for the outfielder dipped at maybe the worst possible time, but at least a glimmer of the lefty slugger at his best reappeared Sunday.

Conforto crushed a first-inning fastball from Trevor Bauer for a three-run homer of the no-doubt variety, helping the Mets roll to a 6-3 victory over the Reds at Great American Ball Park.

The Mets, who trail the Brewers and Nationals by 4 ½ games in the NL wild-card race, still need a miracle to reach the postseason, but will at least arrive at Citi Field on Monday for the final homestand of the season mathematically alive.

“We’re playing for something, and that’s what you want,” manager Mickey Callaway said after the Mets’ fourth victory in six games.

Conforto entered the day in a 1-for-25 skid and owned a .536 OPS in September, having left most of the heavy lifting to Pete Alonso, Jeff McNeil and Robinson Cano lately.

“That’s the frustrating part about it, I feel like there is a lot left on the table,” Conforto said, referring to his production. “And I feel it could have changed the way the season has gone. We still have life, we are going to keep going the rest of the way. I’m looking forward to bringing some consistency to the plate. I think that’s the No. 1 thing I need to work on.”

Conforto said he’s still guilty of falling into some of the bad habits he acquired in his comeback from left shoulder surgery in 2017.

“I think there’s been periods this year where I’ve gone out of my zone and tried to force some hits and force some big moments,” he said. “You have got to let them come to you.”

J.D. Davis also homered against Bauer and Brandon Nimmo’s blast in the ninth against Sal Romano completed the Mets’ scoring. Davis’ rocket in the sixth gave the Mets five players with at least 20 homers in a season — Conforto, Alonso, McNeil and Todd Frazier are the others — for the first time in their history.

After consecutive strong starts, Marcus Stroman took a step backward, as he battled an upset stomach. The right-hander lasted only 4 ²/₃ innings and allowed two earned runs on three hits and three walks with two strikeouts. Callaway had moved Stroman up in the rotation, allowing Steven Matz to start Monday at Citi Field, where he has pitched significantly better than on the road. Also factoring into the equation was Stroman’s knack for inducing grounders — this ballpark is among baseball’s top launching pads.

Stroman, who refused to use the upset stomach as an excuse, was removed in the fifth after allowing a homer to Kyle Farmer and walking the bases loaded. Brad Brach needed only one pitch to extricate the Mets, retiring Eugenio Suarez on a pop up. Edwin Diaz, Seth Lugo and Justin Wilson combined to pitch the final three innings.

“I felt great, my arm and my stuff,” Stroman said. “It’s just unfortunate I walked those three guys in that inning, that is very uncharacteristic of me and it’s kind of frustrating.”

Stroman allowed a run in the first on Aristides Aquino’s sacrifice fly after Joey Votto and Suarez had singled in succession.

Conforto’s homer was his 31st of the season. Alonso doubled with two outs to begin the rally — becoming the first rookie in major league history with 50 homers and 30 doubles in the same season — before Cano delivered an RBI single and Wilson Ramos was drilled by a pitch. Conforto followed with a rocket into the right-field seats.

The blast offered Callaway a reminder of what had been missing from Conforto lately.

“It also reminds you that when he hits one like that, everybody better watch out because his come in bunches,” Callaway said.

“It’s a good time to break out of it and you love that sweet swing.”