Dave,

PIO is pilot induced oscillation. otherwise known as getting out of sync with the control response needed. A slow responding plane, headed down, may get too much up input from the handle, so when it does, finally, turn away from that hard stuff under the flight circle, it tends to go way beyond level.

...and. being a bit sluggish, it might take excess down input to get the turn started...

See where this is going?

Hutch,

A 25' loop diameter isn't necessarily a bad thing. If you prefer tighter, by all means go for it. If you are at all interested in what is now called precision aerobatics, your 46 oz .40 powered model might just be pretty suitable - as others have asked: what size is the thing, and could you post a picture?

Precision Aerobatics (the PC name for stunt) involves several figures that may not be very difficult, except that in a contest, the size, heights, repetition of the same trace in 'consecutive' figures, etc., are more important than sheer minimum loop diameter. Challenging, and can keep one practicing quite a bit.

For fun, find something s***hot and go tie knots in the sky. That's a living ball! CL Precision Aerobatics, because it has pretty stringent defined standards, gives something to KEEP striving at, and the fun angle can wear off unless it can take you somewhere further...

It's all good, and you meet plenty of great guys in CL. Welcome back. (I'll be 70, later this year, btw. CLPA still holds me captive...)