You might be right on that feeling. Moooaaaar power is not always the best idea. And like I said, this combo looks completely wrong to me for an F1 car.

Yes, I think you would indeed do best by getting a new ESC and a new motor. And 21.5T or 25.5T (even slower) is basically what pretty much everyone uses on these cars (on 2S Lipos) - and these should all be way lower than 2000kv.