Stall limiter off

Ever notice a fighter able to suddenly turn around (loop over) and hit you nose first? Here is the rub with limiter off, as you have discovered, at certain speeds your plane will stall, controls will not respond in the "normal" way.
What to do, watch film of specific plane stall maneuvers and try to get close to the same feeling (warning rudder pedals are a must, or at the very least "twisty" stick, but not as maneuverable).
The key, is to practice and learn certain key signs of what to expect your plane to do, and very importantly, how to recover control of the plane. Recognize critical speeds and also know that harsh movements even at "good" speeds may produce "snap" stalls, and are more likely at certain altitudes (depending on the aircraft).
Rinse and repeat, as many times as you have to in order to "somewhat" anticipate what you need to do, in order to control your out of control plane.
For most stall recoveries, these 3 things help me: forward input on stick, reduce throttle, kick rudder.
Once control is regained increase throttle to normal as needed.
I over simplified the process, and with the dual engine P38, you do have more options with dual throttle control.
Most of all, have fun practicing and expect veteran players to anticipate your every move and counter. Some planes however, are more difficult to wrangle, but with the right amount of experience, that may prove to be advantageous.