Help!!!

my mazda 6 is a 2003. and it turns on but it wont go over 5 miles an hour and every light expecially the TA light and the engine light comes on. It jerks violently when driven and it revs on its own. please help. i need this car. it just randomly started doing it. someone said it could be the TAC system. but i dont know how much it costs to get fixed or if that will even work.