Quoted From college man:
when you cleaned the TB on the Cobalt. Did you remove it to clean it?
I need to make an update to the video I did on throttle cleaning as we get this a LOT on the forum and it usually happens after the throttle is removed. Also if it’s drive by wire you should not clean them. There have been instances on this forum where a DBW system was cleaned like that and had subsequent idle issues, the only fix was to replace the throttle body.
Throttle cleaning should only be done if the throttle is sticking and NEVER on a DBW system, I also do not recommend removing the throttle assembly for cleaning.