Boxster running poorly

[e.roc]

Hi All, new to this forum. Thank you in advance for any advice.
I have an 2001 2.7 L boxster. Recently, I decided to check the air filter. Upon removal the foam from the filter was disintegrated and laying in the bottom of the filter box. It was vacuumed clean and a new filter was installed. The next trip the car ran very poorly, and the check engine light came on. The entire intake has now been dissembled and cleaned (found a few more pieces) and the car is still running poorly. No, middle torque. My mechanic scoped the car and found codes for the O2 sensors on both sides. He figured that since it was both sides that it probably wasn't an O2 issues but something else. Another thing that he noted is that the car is running very rich. He is not a Porsche guy just a good friend and a good mechanic. So, he wasn't sure what NORMAL should be.... When the car is started from cold, you get a puff of black smoke. We were going to start testing the fuel system for issues but he is off work for the next two weeks and I would like to drive my car before summer is over. Any idea of things I could check myself? Could this be a fuel filter issue, Mass Air Flow Sensor, Maybe the O2's are bad? Not sure which codes, pre or post. Any ideas? Side note, I have also developed a parasitic drain.... Any chance these issues are related?

[BYprodriver]

The MAF sensors are sensitive to dirt etc so it may be fouled, disconnect the connector to MAF & drive to see if drivability improves with the default program. Charge battery 1st since it needs 12.5 volts to run best.