I just laughed as I installed a $13 motorcraft oem air filter into the air box. On sale at wallmart. 19.2 mpg on a recent road trip…OCD knows no bounds.
Problem solving skills are lacking.
Do you have your original air filter system? (Please tell me you do)
If you want to prove your theory that the CAI is caused a drop in MPG. Reinstall you factory system and drive it for 60-90 days.
You won't be lacking in HP as the factory system breaths very well.
My bet is that you like the sound and as such are in fact driving more aggressive because it pleases you to hear the sound of the engine "breathing better" (hint: sound does not equal power).