[clickman]

To close the circle:

Checked the wires and coils. Nothing loose.
Cleared the codes and started up.
Codes didn't come back (have been thru a few drive cycles since.). No feel of misfires.
Tapping was still there. Went for a gentle drive for about 10 miles and it went away. Hasn't come back (knock on wood.)

Thanks again for the responses.