Not sure what to suggest,but i have a funny feeling and its only that ??its the control on the side of the butterfly that has a lot of sliding paths inside of it ,this control is responsible for the amount of fuel going into engine .Now this may sound stupid coming from a mechanic but take vehicle to dealers and have it serviced as the mechanic will soon pick it up and know exactly what part to change saving you money in the long run.Modern cars are becoming so complicated with all this emmision stuff that unless your working on one brand all day and every day then what works for one make is different to another its a disaster for the likes of general bodgy old grease monkey like myself .But check the rubber pipes that lead to the A/C valves/controls on the left side of engine compartment at back as i done one not long ago and it had an air leak in that area so i changed the rubber ends of the pipes and it was perfect.Just changed the clutch for the same owner last week ,what a ball ache of a job took me a total of 5 hrs.