lagy at low rev help need help
 

hi how are you every one i need help today i was driving back from my mate house normaly and i stoped at the lights and i was trying to take off normaly but my car wasn't moveing and so pushed the gas pedal harder then nothing the few sec later the car starts moving then another stop same thing at got home and just idling my car and it really unstable at the low rev like 750-900 and it moves up and down up and down so i opened my bonnet and asked my mate to just rev the car then i can hear something in the engine(from that area) but at idle makes no noise and my mate that was there said it sounds like it exhaust i don;t know i feel like crying now don't know what to do my car is a 4speed jdm AT that done 56800km and i did change my coil like 9000km ago i have no idea what the problem is need help