If you're using the "Stock" game, the Gato has issues with the mouse-controlled rotation, but CapnScurvy made a mod for that:
Gato Sonar Bearing Fix_Stock
Be sure and read the ReadMe info.
If the AI in the stock game seems a bit "strong", and you've noodled with mods before, you might have trouble with the Save folder contaminating your game folder, causing you issues. Delete the "C:\Users \UserName \Documents \SH4" folder and its contents. You will have to re-set all your gameplay options and screen settings (you'll also lose all game progress), but you'll (hopefully) be rid of the weirdness - unless the game folder itself is "infected"...
