2004 chevy trailblazer

It wouldn't be the transmission slipping would it?

No. It’s probably an idle air sensor or the throttle position sensor located in the throttle body. U have to buy a new throttle body since the throttle position sensor is part of it and can’t be removed. I took seafoam throttle body cleaner and spray the heck out of it which helped then took the whole throttle body off and cleaned it to nlooking new. Runs awesome now. They say not to do that cuz then it has to relearn how to run smoothly again..just unplug ur battery for a day..two days if possible..plug it back in and drive it nicely but as close to normally as u drive for about 30 mins taking it onto the hiway as well as around town with stop and go driving...it should smooth out. Also, Lucas fuel treatment is a must to clean up ur fuel lines and system as well as keep the throttle body and intake clean for longer..better fuel mileage..and more horsepower. The fuel quality these days is what kills off a lot of these newer emissions vehicles early. When ur spraying water into ur motor because they mix it with the fuel..u haven’t many options.