I had high idle issues replaced the MAF which fixed that but now my car idles on the low side, sometimes bouncing from 600-700 rpm, Like a lobing, or cammed idle. when I turn my A/C on it tends to fix it a bit but still it bounces around but usually less, it only does it once the engine warms up. Sometimes it throws a cel, but then it'll go away after a few days, and then back again.

I notice sometimes it seems like it is running rich, I'll see some black smoke when I get on it. not in limp mode car drives fine. Gas mileage seems normal 240 highway 180 city.

Could it be my 02 sensor, and which one? or is it something more serious? I could have the cel red again but I had it done once it didn't seem to reveal much.

 

have you check your fuel pressure reg. vacuum hose?

 

My idle occasionally has a slightly rough idle but it only lasts for a few seconds and goes away.

 

My car just started doing it here lately too i have no idea what it is