Ok here's my problem. My check engine light came on a few weeks ago and I went and had it read, the guy said it said "system too lean". He said I wasn't getting either enough air or fuel. I had just changed my oil so they also changed my air filter so we ruled that out. I bought a fuel cleaner and went and added it and gas and then went home and unplugged my battery for a while so the lights could reset. It was fine but then a couple of days later the light came back on. Then I started noticing that if I was in park with my a/c on it would idle a little rougher than usual. Then it began to get worse- rough idle in park with or without a/c on, rough idle in drive with a/c on then it also began to rough idle in drive without the a/c on. I had the light read again and it still just said "system too lean". I told the guy my problems and he said it was my IACV. He made the light go off and I bought yet another fuel cleaner. I also had began to notice a "losing air sound" coming from my car. We checked and the little elbow that comes off the intake and connects to a hose that goes to the exhaust was completely messed up. My dad changed that and my IACV and then my car worked fine. Well, I started feeling it again. The lights come back on and it's rough idling in park again. My car is an automatic. Any ideas?

 

Did you change the fuel filter itself?Opposed to just using the cleaner?