Before I go looking for a new (used) ETA, I thought I'd throw this out there to see if there are any other opinions. My idle intermittently surges from 500 RPM to 700 RPM while in any gear (including R) and not moving. It surges at a rate of about one or two cycles per second. When I move the gear selector to N or P the idle smooths out almost immediately.
I just replaced the NSS, ignition module and crank position sensor, but it hasn't resolved the issue. Occasionally on a start (usually when cold), the idle will stabilize abnormally high, like 900 RPM. Restart the engine and the idle is back where it should be -- around 500 RPM.
The codes that have consistently appeared after clearing all codes and then checking them four additional times after driving are as follows:
Module 7: DTC 2 (points to a bad ETA)
Module 17: DTC 18 (crank pos sensor magnets not recognized)
Module 19: DTC 6 (ISC inop)
The ETA (non-ASR) was replaced by a prior owner about 100,000 miles ago with a rebuilt unit. Maybe it's time for a new one.
Any thoughts would be appreciated.