I bought a used 2015 Kia Optima LX 2.4L with 80,000 miles on it. Engine seized not even 3 months later of owning it lol other then that, I've never had any other issue! As someone mentioned above, I would try cleaning the throttle body...pretty easy to access, I have done this myself using valve cleaner
Well it's a moot point now. Never found the issue, but I decided to trade it in. Now driving a 2021 K5 EX. I am really going to miss it as it was a one of a kind vehicle with loads of after market goodies. It was a real beauty.