I have gotten the message “Overencumbered! Running will drain AP?? How To fix?” and now I am running super slowly. How are you meant to fix this?
In all of the Fallout games Over encumbered means that you have too much stuff in your inventory. Unlike games that have fixed inventory, you can pretty much collect whatever you like in this game and there is no limit. The drawback of pickig up too much is that you become over encumbered and this comes with lots of annoying side effects.
Open up your inventory and look over the items you have. At the bottom left you will see a number where the left will be higher than the right. 200/160 for example. This means you can carry 160lbs but you have 200 and this is the problem. You will need to start discarding stuff you do not need to bring it down. If you can find a crafting bench, you could scrap junk which may bring that number down enough. If not, scrap or sell some weapons and armor you do not need.