Morning Dave
Welcome to the Forum
The fact that codes are self clearing would indicate they are symptoms not the cause. Check the Mass Airflow Sensor and the Throttle Body I have experienced faulty units with both that didn't throw codes. Your restricted performance would make me think first throttle body or throttle pedal position sender as a starting point.
When you scan are all control units seen or are some not responding? (Greyed out)
Good Luck
Dave