I have the same problem but i believe it is in the servos stey still work fine but they are the only thing that hasn't been replaced.did find a place that rubbed a bare spot on 1 of the servo wires and taped it and things seemed much better but now it's back to glitching again.hasn't fell from the sky again becouse i am afraid to take it to high or to far away till i get some new servos.another thing i am questioning is the extrem 180 bb moters.notice a lot of sparks in them don't have much time on them yet maybe2 hours tops so i haven't canged the brushes yet with the others that came with the moters.but i'm betting on the servos myself.
Rich