you should understand why naruto became the "loud, unintelligent and stubborn kid", this is because naruto grew up in a hostile environment without real friend and without someone who support him grow up. put yourself in his shoe, i mean, statistically, most of the juvenile delinquents has a poor familial structure. though i bet naruto now, when he has all the answers he has become cool, calm and collected... you see, the difference now? when hes that he can be a genius, take the rfs as an example, the way he got the hang of rasengan and most importantly the way he mastered the sage mode in a small amount of time...