i did not read through the complete other thread nor this one so please forgive me if its been covered.
I had a similar issue with my car and i wracked my brain and did many of the things you have done. and at the end of the day it was the oil filter and it was bottoming out before the thing could seal. it turned out the crappy filter gasket was so thin it did not allow it to seal before the filter bottomed out to the motor
