Try flying by adjusting the trim. Using the constant angle trim will keep the plane trimmed when diving (at that angle). Once you are at speed, say 400 ias, use up trim to bring the nose up. That kicks out combat trim, btw.
Flying by trim helps with gunnery by not having to aim above or below the plane you are attacking because of g's pulled from slight stick inputs. Applying zero g's (other than gravity) will allow the guns point of impact to correspond to the gunsite. Any stick inputs during firing requires corrections due to pulling g's.
Another approach is to practice gunnery with a fixed trim configuration (i.e. combat trim off) that minimizes stick input at attack speed and scaling the stick so slight inputs have a small effect. If you are BnZ, bleeding E by slowing down is not the best approach. But if that's what you want to do, then have fun!
Regards,
Malta