Increased idle with O2 Sensor plugged in?

[tomstin]

I've been going down the long high idle road and completed all the usual suspects (smoke test, throttle position switch, temp sensors, ICV etc.) The car seems to idle reasonably well in the 900 - 1K range. That is until the O2 sensor is plugged in, then it idles up to the 1300 range. New O2 sensor from BMW, heater circuit works, output seems to be within range and varies as the manual states.

Any ideas? Thanks!