I agree with the excess air leak somewhere but where...

There is no EGR system on this car. It uses the "flame trap" approach. All tubes where clean except for traces of oil. I removed the oil seperator and it appeared clear, but I did not pressure test it to see if there was a leak. I will remove the oil seperator and apply silicon to bottom to insure no air leakage around the box. I just replaced the o-ring before the test.

Still wondering if the o2 sensor can bias a reading, ie if it mistakenly gives good voltage signal when the o2 is higher. An example. A good o2 sensor is suppose to read .5V in the perfect balance of o2. Is it possible for the sensor perfect o2 balance to rise so that its new mean point is a lean condition and it oscillates from that point?

I would prefer to fix the problem rather than hide it. I have tried two MAS sensors and still get the same reading.