My fuel comsumption is back to normal (~19 MPG). It looks like cleaning the MAF and tightening all the worm clamps helped.
I tested for vac leak with brake cleaner. I sprayed all the intake joints twice without noticing any change in the RPM. I then sprayed a little bit of brake cleaner in the airbox to see by how much it would raise the RPM but nothing happened. I am really not sure why, should any brake cleaner work?
I noticed a pretty loud "air" sound when I depress the throttle quickly. It happens for a fraction of a seconds before the RPM starts to rise. I made a video of the sound. I am not sure if it's normal
Here is the AF Learning data from the AP: