No idea who this was or why they did this - they were tailgating me for about a mile or so then when the lane widened the sped up around front and cut in front of me - slamming on their breaks, I almost hit them, so I slowed down and they did too, I could not pass them, suddenly they sped up again, then slammed on their breaks- again I almost crashed into them, I picked up my phone and dialed 911 - I think they could see my phone because then they took of speeding away as fast as possible! This person is dangerous and aggressive for no reason - maybe they were upset about being stuck behind someone who actually drive the speed limit- but they are dangerous and potentially unstable.