[Raptor]

From what you are describing, I would think your original assumption would be more accurate. It sounds like any load on the drivetrain is affecting it. Retorqueing the sensor is a good idea and you probably should, but that shouldn't be any different based on driveline load so I doubt that is the problem. Maybe your exhaust is hitting something slightly as it would change orientation when load was put on the motor boosting or not. Something along those lines would be my guess.