Long thread but the problem has been found. Intake gasket slippage when installed it appears. Double gaskets, no sealer, except at water ports and the intake side slipped a bit as you can see. Kind of the sway back horse look of one gasket in the photo. It dropped down just enough not to seal up the intake side from the valley and started sucking
oil and pinging/ratteling on the the two middle cylinders where the gasket failed. Or the builder failed. Something failed.
I'm putting a SCE premium gasket back in and really temped to seal it up with something......I still have two unopened tubes of Hylomar Blue and man it is tempting to coat that gasket, stick it to the head first and hope I never have to do this again.
Pictures for those interested or still suffering. The manifold was installed with a double gasket, black side to black side. It easy to see where one gasket slipped down and uncovered the intake port to the valley. Those are the middle two ports and the intake side looks droopy in the picture. Just enough to really create a problem. I don't know why the double gasket, or maybe that's the way the Corteco that failed is designed.
This is the first time I have been confident that I really understand and can see the problem. It all started with a one side ping, got worse, started using
oil like crazy but little smoke and it comes down to a failed intake gasket. Actually, I'm pretty happy. Could have been much worse, assuming this fixes it.
Hope this helps someone (including me).
Thanks for all the posts. I'm on the way to recovery!