The mitsubishi gdi engines are amazing when running right but they are prone to a few faults including this one
Had a similar thing on my chariot. It is usually engine clogging with carbon somewhere/somehow which is a problem on the gdi engines.
Hopefully it ill be the throttle body which can be cleaned. It is a bit of a pain to do and cant really be done in situ so I just replaced it using a decent used one. There is a breaker on ebay who is very reasonable.
If that doesnt work it will either be the injectors which you can only get oem and they are silly money.
Or it needs the valves/head cleaning.
Hope for your sake it is the throttle body.
Good luck