Throttle potentiometer / running too rich

[glenn]

Hi all, first time poster here.

I recently acquired a 1993 Citroen BX16 TGI from a friend of mine. The car had started acting up and he took it to a local garage, where they thought it was an ignition problem and blindly changed the ht-leads, plugs and rpm-sensor. After nothing changed, my friend gave up and eventually sold it to me.

Now, when I got home it was obvious my 'new' BX is running way too rich. I've tried unplugging the lambda and (what I figured were) the temperature sensors without change. Am I right in thinking that the throttle potentiometer is the next likely culprit? (there is no air flow sensor)

So my questions are: What kind of values should the throttle potentiometer read when open/closed? Should I measure voltage or resistance? I tried borrowing the Haynes manual, but it didn't even list my model. The Citroen's engine says: Engine Type: BDZ.

Thanks in advance, hope you can help.