Gently push the small vacuum tube connected to the MAP sensor while it's idling to see if it makes any difference in performance. A failing MAP sensor and/or cracked vacuum tube is fairly common on the first gen Aveos, and yours are suspect, based on the symptoms you've described. I normally always recommend diagnosing instead of just hanging on parts, but a vacuum pump is required in this case to test the MAP sensor. So if you don't have a pump, it's less expensive to just replace the MAP sensor and also that vacuum tube at the same time.