[FernyT99]

I have a 2016 Limited LT with the 1.4, occasionally when I am idling at a stoplight or sitting in a parking spot for too long with my A/C to the 4th notch my car with try to die and fall below 400 RPM and I have to rev it to get it back up and running proper again and when I sit too long in a parking spot and put it into drive it'll due the same thing but only when I have A/C at the 4th notch and even rarer on the 3rd notch, I live in Arizona so I NEED my A/C lol. I have been told that it could be due to a failing turbo or wastegate and at 75 MPH on the highway after about 30 minutes I get an under boost code so I wouldn't be surprised. Thank you

 

[Thebigzeus]

Rough idle or stalling is usually a vacuum leak, would also explain the underboost code. Have you ran a boost leak test?

 

[FernyT99]

not at all, it's my first car and first car I've worked on with a turbo, no clue how to do that.