well my car has just started acting up at idle. the car will drop to around 400rpm then rev to 1200 or so and just keeps doing it untill i give it some gas. it also happens when i am driving and hit the brakes. anyone have any ideas thanks

 

did it just start doing it or did it happen after changing something out? Check and clean the mass air and check the iac and clean it of any gunk or debris if there's any.