You've already said HUGE PROBLEM. I have to agree. Take it to your dealer or other trusted mechanic. My bet's on electrical or ECU problem. Well beyond DIY. May be something simple or loose, but IMO you'd be looking for the "needle in a hay stack" trying to diagnose it without the proper equipment and knowledge. Could it be a loose connection? Sure it could! And a stopped clock is right twice a day.:| But my guess is you'd be wasting lots of time for little to show for your efforts trying to second and third guess the problem. Good Luck.