Have you tried reinstalling them by any chance?
Case in point, back years ago we all flew the 1% AVHistory F6F-5's in squad competitions and I experienced the same as you as this particular aircraft was a slug and resulted in my being shot down several times vs. the other 1% F6F that I used in which I did fairly well. It simply didn't make sense since no one else had any problems with it. Frustrating to say the least.
Long story short, a simple reinstallation cured the overly sluggish F6F-5 characteristics that I experienced.
This is where I would begin, hope it works for you.