hi this is a common problem .most times all i do is take off the air intake pipe to the throttle body ,u will see a round disc called a butterfly .which as u press accelerator opens up . this gets carboned .or oiled up , get a can of carb cleaner from yor local motor factors and clean it ,then make sure its held open and clean as far as u can inside it ,,watch out they can be very sharp .u can also use brake fluid ! but be carefull not to get any on yor paint work ! hope thats of some help to you
ade
October 2009