08 Vue 2.4 rough at startup then smooths out

Hello. I just got an 08 Vue. When I start it up cold, it has a bit of a rough idle for the first 15 or so seconds, then smooths up. There aren’t any engine codes showing. It doesn’t do this if it is already been driven recently. I tried changing the spark plugs and boots already. Anyone have this issue before that can point me in the right direction?

 

Haven't had the issue, but are you using the OEM plugs? Also, you don't state the mileage, so based on its age, I'd recommend a bottle of techron to clean out the injectors, and a throttle body cleaning. The throttle body plate can get very dirty and not smoothly move to where it's supposed to be, slightly changing the air fuel mix.

(Although the 2.4L Ecotec is a direct injection engine, it still uses a throttle body)

These are cheap periodic maintenance things you should do anyway, and they might solve your issue. If not we keep looking.