Almost caused a wreck by speeding to pass our vehicle, then breaking roughly, forcing us to slam our breaks to avoid a collision. We proceeded to move into the next lane to pass calmly, however, that angered the old man. Followed by him speeding next to us for awhile, while yelling and making gestures towards us. Was an older white/gray haired man. Plates say “in god we trust” with a Performance Bountiful plate cover.