Hello,
you have to change the Rudder Delay to 0 - 2 first. See this table:
http://manual.spirit-system.com/index.p ... o_list#MKSThen Pirouette Consistency should be at least 170, but not more than 185.
Value of 117 is actually not possible to set, I guess you meant 171.
Changing these two parameters should help a lot, but first it is recommended to set it so that the tail will hold well. With this servo it should work quite good.
How did you configured mechanical tail center position? When ticking Servos/Subtrim (tuning) all servos - including tail servo should have arms at the center as close as possible. At the same time there should be a slight angle between tail blades - just as described in the manual of T-Rex.