OK, I'm not clear on how road rages comes down to a choice of the alternatives you have presented, but assuming you are outlining a self defense situation, then typically what will be evaluated by the court is whether you responded reasonably. Is it reasonable to shoot someone because they upset you with their inability to adhere to even minimum standards of driving proficiency? I suppose the answer to that may depend in large part on who you have on your jury, but even the president of the NRA might think it was a bit of over kill, pardon the pun, to shoot someone over bad driving habits.
Most courts will look at how you respond in a given self defense situation by first asking whether you were reasonably in fear of your life and limb from the alleged attacker. If you have mutually stopped along a road side to have a confrontation, you may have already removed the element of reasonableness from your defense, as it may be considered unreasonable for you to have even stopped. In some states, you must take advantage of an opportunity to escape. If you had a chance to leave, as in the Con Air example you cite, and do not avail yourself of the opportunity, again whatever actions you take, may be deemed to have been unreasonable.
Next, your level of response will be examined for reasonableness. Also, did you break off your defense once you were no longer in reasonable fear. That is, once your attacker is down and no longer able to attack or pose a threat to you, did you continue to attack him? Or in hardware terms, don't use a blow torch when all you need is a match.
Finally, while you are measuring time served, you might also want to toss into your risk analysis the civil penalty price you may end up paying if you are found to have acted unreasonably. O.J. may not be in jail, but he's not living in Brentwood either.