running a little rough

[RF600]

I'm hoping someone can help me out. I went to get a smog check and the HC's were good then they went high. Good then high. The guy doing the smog said it would likely fail, so he didn't do the test. There was a light popping out of the exhaust as well. I believe it's unburnt fuel that is causing the issue? I have done recently, plugs, wires, cap, rotor, fuel filter, oil change. 

 

I pulled 1 plug and it looked lean. The electrode was pretty white in color. I have a different MAF and it didn't change how it ran. Yes it's used, but I figured I would try it. It starts up great, no issues there. I have not tried to pull any codes. No check engine light, so I'm expecting no codes to be present.

[Slartibartfast]

So it's going back and forth between good and high? The mixture's actually supposed to bounce back and forth a little when it's in closed loop, that's how it controls the mixture with a narrowband oxygen sensor. Maybe the sensor's on its way out and it's responding very slowly? There is a test mode for the oxygen sensor, might be worth running that to see if the light's flashing like it should. 

 

Some codes don't trip the light, so I'd run those too on the off chance.

[adamzan]

The o2 sensors are so cheap, I'd just replace it if you're unsure of it's age/status.

 

Make sure the timing is correct, as well as egr, etc is functioning correctly. I hated doing this test when they had it here, would always fail and make me waste hundreds of dollars.