Brake boosterrrr issueee

[NickT64]

Hey guys, so I have a 2013 Ford Edge Sport and have had to replace the Brake booster because of extremely Stiff brake pedal. I did so and replaced it with a cheap duralast brake booster from autozone. Found out it was a remanufactured part 🙄. Anyways I replaced it and not only do I hear air leaking when I press the brakes (after replacing the brake wasn’t stiff and felt fine) but also I hear air even when not pressing the brake at all. I checked the vacuum hose and it was fine. I’m guessing I got a faulty booster. Or maybe I’m thinking I need a new O ring for where the master cylinder goes into the break booster. Also my idling was so rough that my engine cut off and got a low oil pressure warning because of it. Do y’all think it’s just a faulty brake booster that I got? Or something else?