If the airplane dips to the left with back stick, could it be P factor..? Light airplane, big engine/prop mass in relation.

Not to repeat, but are you sure the servos move at precisely the same rate? Not deflection/travel, but exactly the same speed to get to full up from center? That's my problem I believe, why mine dips. You can see it on the ground, a hair difference that results in roll input on top of the increasing elevator input until they stop at the stick setting.

MJD