84 Porsche 944 Bad Oxygen Sensor?

[CarterH944]

Lately I have had some weird engine idles on my 1984 Porsche 944. I started it up the other day and it ran fine, after about a minute, it starts to hunt for an idle. Drops down to about 700ish and then up to just over 1000. Give it some gas, and it gets worse. Turn it off and then start it back up and it instantly starts to hunt for an idle, give it more gas, and it stalls out. Curious if it's an oxygen sensor, distributor cap, or anything else could be bad. I'm going to unplug the oxygen sensor and run it in the open loop mode. But if that isn't it, any other suggestions? Or could it be the oxygen sensor? Picture of oxygen sensor is attached to see if it's original.