I've built the Tiger 2 and Tiger 60... once the fuselage is glued up, if it's not straight, it never can be.
Check as Angueto mentioned for engine/fin fore-aft axis alignment.. a wing warp, non-zeroed surfaces...
Something must be awry.
T-2's are also notable for aileron flutter. Long skinny soft wood ailerons with a center drive are easily excited to flutter. 2 servos work better.