You may have plugged oil passages on the rockers on that side of the engine. If VLA collapses due to lack of oil (and can't be re-bled), then it will be constantly banging between the rocker and the valve. I admit, this is speculative, but I'd make sure all oil passages there are clean and not obstructed.

 

The rocker shafts were all clear. Small and large holes Didn't see anything on or in the head. Hopefully that was just coincidence.

 

In November 2014 I removed all the intake butterflies from their two shafts because one or two screws had come out of it's shaft mounting point and gone missing. I don't recall which side or intake butterfly had lost a screw. Is there ANY way the screw could have been injested into the cylinder and then ended up in the oil system? I think it would suck into the cylinder from intake and be blown out through exhaust valve. All cylinders had good compression at that time in 2014. That's the only known thing that could have clogged anything, but I don't know of a way for that tiny butterfly screw to have made it's way to the oil system.

I will stick a magnet into those oil ports of the head and see if anything comes out. Is there any other way of checking for larger metallic lodged debris?