[Shifu4x4]

I have a 2015 Veloster Turbo (auto), currently at 59,000 miles. Car started to do a weird misfire when I press the gas pedal at 70% +.Tried 93 fuel with fuel additives to clean fuel injectors and replaced with Denso Spark Plugs (with the correct gap), but it was still misfiring. Took it to the dealership since it was still under warranty and they replaced coil packs and re-flashed the ECU but the problem persisted. Car has been at the dealer for 3 months now and I have received no update.
Is there any idea what it could be? I would really appreciate it.

Here's a video of the issue:

 

[GSC2019]

I'd take that in to the shop

 

[GSC2019]

Check your engine valves, any excessive blowby. Do a compression test

 

[trdtoy]

If still doing it after proper plugs and coils then it will most likely be fuel line unless you have other issues unknown.

 

[Shifu4x4]

Car is completely stock. So far the dealer hasn't been able to identify the problem yet.

 

[trdtoy]

Be sure proper plugs, gaps, and OEM coils. I've seen even dealers get this wrong. Also run good 91+ pump gas in it. If it misfires after this on the OEM tune it will most likely be the fuel line as the culprit.