It's probably the ignition tumbler. It's super easy to take out, there should be instructions/videos on the internet.
Whatever you do, do NOT try to spray lube or grease in there. That will just attract more dust. If your ignition lock still works intermittently, take out the lock cylinder NOW and rebuild it because if it gets worse to the point where you're not able to turn it to the ON position, you will not be able to get this out as easily.
You can buy the official Ford kit off RockAuto, or the Strattec kit and rebuild it to use your existing key. The aftermarket kits don't let you do that and only gives you a brand new key which is inconvenient for the doors. Chances are you might not even need to buy the rebuild kit. You can take out the lock cylinder, take out all the parts and clean every single piece, especially the wafers. If you are really cheap, you could even grind down the wafers a bit. Once you have this apart, it's pretty clear how the part works.
Usually what happens is dirt or lint gets stuck in there and affects the clearances so it won't turn. The Strattec website has instructions, but I found the Ford kit has clearer instructions with diagrams. It's a bit tricky at first but you do need to take out every single part to clean. Blasting the lock cylinder with air or brake clean won't do it.