I'm working on an original 69 pace car and having a problem with the R/S headlight doors.
Everything works fine until you shut the car off and about 5 seconds later the Rt door opens half way and the LF door opens about an inch or so.
Replaced check valve
checked all the lines ( yes they are old but seem to hold vac.)
Anybody have any ideas before I throw lines in this car
# 303 489 1872
Thanks Steve

sounds like the vacuum switching valve is bad. The diaphram on top of the valve is loosing vacuum. When that happens the doors will open.
Here's some info.
http://www.camaros.net/forums/showthread.php?t=156303&highlight=vacuum+switching+valve

What I don't get is they open AFTER the engine is off.(no more vacuum except the reserve tank) Strange. Maybe it's valving from the tank. Try, with a helper, having them shut off the engine and you pull the hose from the tank instantly. See if they open then.