Sounds to me youre bottom end is almost shot, If u decide to tear down the bottom, I would recommend replacing all the bearing @ once, cause just replacing one, Others will fail in a short time.
Good Luck.
You just might get a few more miles from that engine...
When torn down let us know what it was....
The VR4 guy got back to me and he said his noise went away with RPMs also. So this is where I'm headed.
I'll slowly do this after work each day and hopefully this is it and post back what I find.