How hard is it to change an air filter? Been waiting on my mechanic for a while and thought I might try it myself.

Extremely easy if you can undo 4 to 6 screws . locate big black box undo the screws surrounding the top remove top remove old filter replace new filter tighten screws job done ten mins max

Ok, do I need to unplug the air flow sensor?

Yes you can do it will allow you to lift the lid higher also hoover out the box there will be leaves and dust in there