Given more or less equal circumstances, a Spit5 or a N1K2, Ki-84-Ia will eat a P-38 alive in a slow speed fight - whatever version it is. The Ki-84-Ia, in particular, once its own superior set of fowlers extend, can do anything a P-38 can, and do it much better.
The problem with evading a P-38 is that the P-38 is more than capable of following a turn long enough to gain a firing solution once it grabs onto a certain advantage. That's where its natural advantages in torque-less maneuvering kicks in.
For instance, if a P-38G grabs hold of a Spit5 from an E-advantaged position it can turn about one full circle with it with gun solution. It means the P-38 is capable of pulling more than enough lead to get a shot in for more than a full circle. Only when the fight becomes much longer, over two circles, and the speeds go down to 100mph+/- levels, will the Spit5 start gain ground in the turn fight and manage to decisively outturn P-38s if it continues(but this is usually the point where the P-38L or a J levels out and just runs away).
Ofcourse, rarely does the fight take that long in most cases - a half circle or so and the grouped .50s and the single Hizooka usually makes short of the target.
Ofcourse, above analysis takes as a premise that most P-38s also fly higher than anything else around, so rarely would you see a successful P-38 pilot ever engage anything at co-alt, slow speed, at fairly equal starting position. No matter the big words and chest-thumping, basically, a P-38 will come from above you, and then latch on to you, denying you an equal chance in the merge. (But of course, securing the initial advantage is really the basic of all basics in ACM and that's nothing to be criticized, or be ashamed of, for both sides).
But that also means that if for any chance a SpitV or a N1K2 or a Ki-84-Ia finds a P-38 that doesn't have enough speed to run away from it, the tables will be pretty much easily turned if the particular Spit, N1K, Ki-84 pilot is a decent one. Anything the P-38 can do at a disadvantaged position, these planes can follow easily.. unless the pilot is inexperienced and doesn't know much about throttle control, rudder input, or flaps.
So basically, once you see a P-38 within 1k distance behind you and closing, you're too late to do anything. All you can hope is do whatever you can and hope the P-38 pilot sucks in gunnery, so you can turn long enough for your natural advantage in turning starts to show off. However in most cases, a half a turn and you'll probably be in flames or missing a wing.
Therefore, if somebody claims that the P-38 still matches the Spits, N1K2s, or Ki-84s in maneuvering, without the above described situation in place, that's actually the same thing as admitting the FM is entirely wrong, because there's no way a 10 thousand pound plane can match a smaller plane with better powerloading and lower wingloading toe-to-toe in every bit of slow speed maneuvering - with or without flaps.
