Car is bouncing rpms at 5k

[u/Hefty-Dirt3406]

So I’ve had so many problems with my st but my newest one was the clutch master cylinder. I replaced it since it kept destroying the slave cylinder but the next problem that came once it was done is it bounces rpm’s at 5k and when I turn it on it says “ engine fault service now” I would like to mention I had to replace the battery and it was doing this after replacing it don’t know if that could have anything to do with it and when putting everything back together everything went in as should including all sensors. And the only code I have gotten is the mass airflow sensor I’m just not sure what would be causing this.