Yeah it happens in Park or Neutral as well. Just rev her up to a certaing RPM, and you got your nice metal tapping noise happening. Mind you I have noticed a power lose at the higher RPM sometimes, might be complete unrelated tot his problem though.
The strange thing was when we undid the support arm bolts for the auto and tightened them up again, surprisingly most of the noise went away and fixed some of the problem. This makes me think that either the metal backing plate is flexing inwards and hitting the torque converter somehow(because the support arms crush against it) or the auto transmission is not aligned properly which i don't really see how it couldn't be.
This car is sending me crazy... I fix one problem, only to end up with another!