So I have had my Legacy for about 3 years now and it has run fine up until about 6 months ago when the CEL came on. I took it to Autozone and they ran the computer and said the airflow sensor was out. I bought a new airflow sensor took it to a local car place and they replaced it. When I got it back from them, the idle was running way low and every time I come to a stop the idle chugs down almost to zero (doesn't stall but gets close) and then goes back up and continues the process until I start accelerating again. I have noticed that other year Subarus get the IACV gunked up and it can be helped by cleaning could this be my problem?