Anybody got the VW part number for the shielded green wire for a 1.9L Digijet O2 sensor?

Lately I've been getting some really funky readings on my Digitool with both a Bosch OEM sensor and a generic Bosch cut-and-splice 1-wire.  The readings have been generally high (I think due to other issues) and the engine bogs terribly on acceleration while the readings suddenly go negative!?!  Pushing the pedal down far enough to activate the full throttle TPS gets it rolling okay and the readings (while still a bit high) go back to bouncing around in the positive range.  I'm not an electronics whiz but I suspect the only way this could happen is a short between the wire and the shielding.

Chuck
'85 Wolfsburg Westy - 'Roland the Road Buffalo'