Odd pitch problem with sharp throttle adjustments

Hardware Multirotors
1

I have a 250 with an APM 2.6 FC. It hovers nicely, maintains its position and otherwise doesn’t goof up unless it is something I have done…UNTIL…I give a burst of throttle. When coming from a take-off or get on the throttle heavy, it will pitch up at a steep angle. This makes for some sketchy take-offs and some erratic flights if I am not going low and slow. Frankly, because of this pitching up I try not to give much throttle unless it is slow and deliberate.

TX is a Spektrum DX6
FC: APM 2.6
GPS: Aerosky
Motor: Multistar Elite 2204-2300kV
ESC: Turnigy Multi-Star 15 AMP (2-3S)

The bind is on a clean Acro setting. No expos and nothing done other than servo reversal on rudder, yaw and elevators. ESC’s have been calibrated as well.
The radio has been calibrated as well.

I have been thru mission planner looking for various settings that might affect this, but I am coming up empty handed.

Attached is the log file for the last flight (which it took a dive because of the pitching up. Possibly hosed a motor up - stiff rotation and the ESC gets noticeably warm after a very short period) in text format.

Any help is appreciated!

2

If this is in the wrong spot to question, would a mod please move?

Thanks!

3

Did a flight to check some adjustments to CoG, which culminated in a crash. I had to give throttle to avoid a collision with a tree and it pitched straight back very sharply and hit a rock due to sudden loss of altitude and my attempts to regain control.
Still have not been able to peg the odd pitch problem.