Air leaks in the intake system of any car can cause erratic idle, hesitation and a lean fuel mixture. The leaks can be almost anywhere downstream of the Bosch airflow meter and can be difficult to locate. The first thing to look for would be a loose hose clamp. If all the clamps are good and snug then look at the condition of the ducting components: airflow meter hose, middle air hose, intake boot and the four runner hoses. All are exposed to high levels of heat and vibration and each are most likely to crack on the bottom side.   On my own car (1982 Alfa Romeo Spider Veloce) I experienced something a little different. My car had both an erratic idle and hesitation. I inspected the hoses and the clamps, each one appeared to be in good condition but there was a hidden issue. I checked the “bellows” end of the hose for cracks in the pleats, it was in good shape. (Photo 1) The bottom side also checked out ok. (Photo 2) At this point I went to reinstall the hose, the clamps were still in place at this time. While tightening the clamp that connects the airflow meter hose to the middle air hose the problem appeared. (Photo 3) The hose clamp had cut the hose all the way through on the top side. It was hard to see because the cut resembled other casting marks on the hose.  I compared the replacement hose (IAP # 01253) to make sure it was correct and meet the quality of the original Alfa Romeo part (60518733) which is no longer available. The original hose was very thin in the area where the clamp cut through (Photo 4) in comparison to the replacement part (Photo 5). It should last much longer than the original Alfa Romeo part.   | 
