Before we check the BCS. we have to look at another issue. From your post, you describe your operation as backwards.
With the car OFF, the arm should be all the way down, with the BCA extended.
At IDLE, the arm should be all the way UP with the BCA retracted.
When you rev in park or neutral, it SHOULD NOT MOVE. The PCM should be in bypass.
When you pull the TOP vacuum line off the BCA, it should EXTEND, pushing the arm DOWN.
Verify your vacuum connections:
The routing should be obvious with the red lines you see here. Ignore the unused port on the BCA (that'* for a vacuum-relief vent, and most of our foam filters deteriorated long ago).
AFTER we figure out why yours is acting funny, you'll want to go back to the rear of the engine to check your connections (vacuum and electrical) to the MAP sensor. The MAP is a rectangular box on a bracket just behind the #4 fuel injector (between the SC and firewall, above the rear valve cover). Small box. One vacuum line, one electrical connector.
Do the carb cleaner test on this one too (at idle).