Hello

I don't know why im sucks at making a fighter jet, am i only good at making Propeller fighter..., so here's the case: i wanna make the long dreamed F-12 Alterra Stream, basically a modern version of F-12 Alterra II which is a small, nimble WW2 fighter that even more agile than a fighter jets, now im wanting to pass on that good trait that the WW2 version have, notably small and nimble fighter jet, its looking good but then when im go ahead to test flight that plane it just goes awol, pitching is a nightmare as the plane itself have something that's called "Control Surface Stall" which make your plane uncontrollable, the WW2 version also have this problem but not on the fighter variant, notably A-12 Marauder variant that have 2x 40mm Gunpods, the Marauder is very-very unstable needing carefull pitching after a dive to enemy location, the F-12 Alterra Stream is problematic as it will start to begin flat spinning after doing full pitch, which mean me as the maker and tester have to be very-very delicate at controlling it, its like a Panther but in the air, so far only one Stream variant that control exactly the same or maybe even better than the old one, if you know FI-506, that twin boom fighter that thing is pretty good but the stream is even better as the configuration is almost the same just enlarged by 1.5, it handle so beautifully, and can also fly to a very-very high altitude thanks to its extra long wing, sadly the first FI-506 use mods which mean that IOS and 1.9 user can't use it, the second problem is when i wanna make another stream variant of an F-250 Valiant, a delta wing fighter plane that already good despite some control surface stall at low speed probably from the use of pitch axis vectoring thrust, it also unstable as the vertcal stabilizer is very small, when im making the stream one i don't know why but it just too agile to be true, it literally do a full loop in just 0.8 second and can outrun and outturn any missile and plane, even AI can't control it, if you want to dogfight with this plane (it only have guns and no missile) you need to be in slow motion as it were moving so fast you cant even fine tune your control, it doesn't use vectoring thrust, it looks like a spaceship and can't even fly at 35.000ft because the wing is so small, and i don't like it being so agile, any help on how i can get my fighter jets to control realistically?