A delusional creep posing as a federal agent followed a woman from New Jersey’s Six Flags Great Adventure to a supermarket parking lot — and then insisted to cops he was a G-man, and had the credentials to prove it: a coupon from the amusement park and a handicapped placard, police said.

The victim called the cops around 1:10 p.m. Aug. 19 to report that a man trailed her car from the theme park to a ShopRite parking lot in Jackson, police said.

There, the stranger blocked her vehicle and tried to get inside the car, yanking the door handle as he identified himself as a federal agent, cops said.

Police quickly arrived and found the 59-year-old sitting in a 2018 Nissan.

As officers attempted to identify the man, he handed them a driver’s license along with a Great Adventure coupon and a handicapped placard, which he claimed were his law enforcement credentials, according to authorities.

The suspect refused to get out of his car and as patrol vehicles zoned in on him to prevent him from leaving, “he abruptly backed his vehicle away and fled the scene, disregarding the officer’s orders to stop,” the department said.

He then “recklessly” drove across the parking lot, over curbs and out onto North County Line Road, where he hit speeds of more than 80 mph, police said.

The chase eventually was suspended, but no matter — a short time later, the suspect’s car was spotted parked on a local road, where he was finally arrested.

The suspect, whose identity was not released by cops, was taken to an area hospital for treatment and evaluation.

He was later released and booked at the Ocean County Jail on charges of eluding, impersonating a law enforcement officer, resisting arrest, obstruction, harassment, speeding, reckless driving and careless driving.

The man also was hit with several other motor vehicle violations.