A little background first. I changed both oxygen sensors - based on prior CEL's coming up. The last one was recent for the front sensor and code was gone for about 200 miles of driving. To get that one out, I had to remove the exhaust manifold and then reinstall everything. I did not replace the manifold gaskets (engine side and cat side) at that time - I know ... I ordered both and will put them in when they get here. I wasn't sure if wiring went bad on the sensor, so I just checked it and seems fine so I put that back together again too. Haven't completely ruled out sensor going bad yet ...

I checked for vacuum leaks with carb cleaner in some areas with no results or changes to engine idle speed. I haven't pulled the MAF sensor to clean it yet. By the way, the car runs great - idle is smooth and response/acceleration is solid.

I'm kind of hoping that the new gaskets might help this CEL issue, but wondering what else I should be looking at? Any help would be appreciated.