My readings came out fine:
+20mA with ignition on, engine off
+7-9mA (fluctuating) with engine at operating temp, idle speed
resistance at EHA, ignition on, engine off: 19 OHM
So, apparently I have a bad EHA or valve seal. I'm gonna replace the seal first and see if my lambda readings stabilize.
Stephen, you're welcome to borrow this harness if you want. Let me know ASAP and I'll send it out today.
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi