I will check the voltage on the x11 in a little bit.

I assume we are talking about the throttle position sensor located on the side of the throttle body?

I disconnected that and there was no change, but that could mean anything.

What are the proper resistance ranges for it? I assume if I move the throttle the resistance value between pins ? and ? will change (since it's a potentiometer)

Try this:
https://www.landiss.com/mixture.htm

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1990 190E 3.0L

This is for the air flow ratio right? I am looking for the potentiometer on the throttle.