The Citabria is a handful by design. It's the combination of a short tail moment (short coupled), a "high" CG, a high wing, narrow landing gear stance, and a mid-to-high wingloading (compared to, say, a cub), and a (usually) high power loading. Frequently the CG is also a bit aft as well (again, by design).

Remember, Citabria is Airbatic spelled backwards. It was designed as an acrobatic plane, and it flys like one, even in model size.