I notice that when you want to gain speed and/or use the sky as contrast to help locate aircraft at a distance, you dip your nose. That in itself is not a bad thing; however the angle of the dip is a bit extreme. If the down-angle is that aggressive, two things happen - 1) you trade too much altitude for speed, and 2) you actually allow the aircraft you are chasing to extend farther away from you. Even though you are going faster than the aircraft ahead of you, all that speed is directed downward and not horizontally toward your target(s). Recommend placing the horizontal bar in the gun-sight about and inch or two below the horizon. This will gain you your speed, as well as help close the distance between you and your target(s), while also gradually placing your own profile below the target's optimal contrast viewing angle (you get lost in their rear-horizon line/ground clutter). Work with Navy on that, he is a master of that technique.
It is a bad habit to follow your quarry to the ground. This has gotten me killed more than anything else. As soon as you see your target lose big portions of itself, or it seems to depart normal flight characteristics, break upwards into a combat turn (spiral climb) so you can 1) regain altitude/restock energy, 2) confirm that your target is no longer a threat (does not matter if you witness the crash or get kill credit, as long is it is out of the fight, it is no longer a threat), and 3) you can get a good look around you for situational awareness.
This is also part of BnZ. Instead of locking onto your target and following its turns - and matching speed for speed - keep your speed up and break high into a combat turn. This allows you to 1) maintain a higher energy state than the target, and 2) also clears the way for your wingman to convert his speed and altitude into offensive angles on the same target. With two or more wing-mates, you can tag team the target and maintain a higher state of situational awareness. This is called the vertical weave. Even if it is a one-on-one and there are no wing-mates there to help, you can still perform the vertical weave. back in the day (Red Baron and legacy IL2), this solo vertical weave was also known as "dancing on his head." You maintain the energy advantage while also forcing the enemy to expend more of his own.
And as you and others in this thread have mentioned, MOAARRR looky behind you.