I have a 2013 LaCrosse with code P0306. I changed out the plugs, swapped coils, and got fuel injection service. Check engine light is still on and car is still missing only on low idle. Could I have a bad injector or is something else the issue?

At idle. What are the fuel trims doing when it sets? Intake leak?

I’m not sure, the dealership did the diagnostic. They said they drove it with the code reader in it and that it only misses on low idle. They also said it’* what’* causing the service stabilitrak light to come on. They didn’t perform any leak tests. It is also a flex fuel.

Time for a compression test.

I'd spray around the number 6 hole and see if it changes. If the miss counters drop you have a leaky intake gasket.

Ok, I’ll try that.

I forgot to mention in the initial post that when the tuneup was done the intake gasket was replaced, also replaced fuel injector after the fuel injector cleaning was done. Cylinder 6 is still showing misfire.

You need to do a running compression test. You may have a bad valve or the cam.