New symptoms of an old problem?

[zorrex]

All righty...A few months ago I got a CEL that would come on for maybe a day, then it would stay off for a few. It had been doing this consistently up until a week ago, code P0133 for my O2 sensor. But, as I said, it hasn't come on in just over a week, which is abnormally long for what has been happening. But just yesterday as I was driving (on my way to a NECO/CEG meet btw, LOL) my car started to idle HORRIBLY. It would run at really low RPMs, and because of my exhaust leak, it sounded very comparable to a deep throaty muscle car idle, only a sh***y 2.0L version LOL. After I drove for a little while, it went away, and my car idled beautifully . I was thinking it was my MAF acting up again (I cleaned it a couple months ago), BUT I DON'T HAVE A CEL! What gives? My car has never run so horrible. It wanted to die on me at every light/stop sign .

 

[Tony2005]

Start by changing the upstream O2 sensor (P0133). If that doesn't fix it, change the IAC valve.

Where is the exhaust leak?

 

[zorrex]

My flex pipe is pretty much in two pieces. I just find it weird that the symptoms would suddenly change like that? Regardless, I'll put that O2 sensor on my list of repairs, lol.