Hi Bill, I believe these are controlled by PCM signals so they get a fairly constant supply of vacuum and in practice, should maintain position even with the bleed down.

It would be interesting to have the owner of similar vehicle perform the same test for comparison. Mine's a 98 so no flaps.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250