G'day mate,

Before I can give an informed opinion, let us know what motor you're using, prop, line length and the color of your undies before it starts chasing you.

sounds a bit like something is not aligned properly. Maybe the elevator not square ?? Check the alignment from the front of the model, looking down the propshaft, to make sue everything is dead square.

Is the motor still pulling strongly at the top of the loop?

Let's know the answers to above and I'm sure the answers will follow.

Regards

Greg