Could be completely wrong about this but I put one lead into pin 3 of X11 and the other to chassis ground. Not sure about using Pin 2, it may work fine as others have said. Pin 1 AFAIK
You need to check your duty cycle with the engine running at temp over 80 deg C. You should see the value fluctuate by around 10% say 45%-55% on the meter. You can also use a dwell meter to read duty cycle, search the archives for how.
There are many reasons you won't go into closed loop here's a few:
Zero position on the Air flow meter incorrectly set.
Basic Position incorrectly set / Mixture way out of adjustment
Malfunctioning sensor - 02/Coolant temperature/Air flow meter sensor etc
Look for my thread about setting the 190 16V Air flow meter, should still be on the forum. Talks about checking zero/basic positions.
Report back what you see above 80 deg. For instance, take her for a drive warm her up then look at the meter.