I hope you will read How to Talk So Kids Will Listen, and Listen So Kids Will Talk, by Faber and Mazlish. The book is abundant with real-life examples of how parents helped set the conditions for a child to address his problem himself. Children can be creative problem solvers, and are more invested in solutions they think of themselves, more likely to work at making them a success.
If he has a quick temper, he will still need your support and patience. But you might be surprised how effective it can be to put more of the responsibility within his reach. I've watched some pretty remarkable turn-arounds in a few families with really touchy kids, in a couple of cases, not much older than your son.
One other thing that may possibly be making a difference: He may have sensitivities to foods, preservatives, artificial colors, or air-borne chemicals in his environment. Many of the ingredients of our modern lives are actually pretty toxic, and many are irritating or stimulating to the central nervous system.
This can have a profound effect on mood. I know from first-person experience, and have watched children in group testing situations simply fall apart or blow up minutes after having a drop of some dilute chemical squirted under their tongues. You might try using only unscented laundry detergent, no fabric softeners (most of these are extremely toxic), and try using baking soda or white vinegar for most household cleaning for a few weeks to see if this makes a difference.
Hunger and insufficient sleep also have detrimental effects on mood and self control. And long/frequent exposure to television and on-screen games seems to be clearly detrimental to some children.
Some kids are just more at odds with themselves, through no fault of their own. Most will grow into greater self-control with persistent help from parents and teachers.
I wish you all well.