I imagine you would have a vacuum hose going to your MAP sensor (inbuilt I believe into the ECU, yes?)
Also an air temperature sensor, yes?
It should be noted that the picture I put up was taken before any of the gear that has to be used to actually run bits of the car was attached.
Note: some of the stuff that you probably have would relate to an idle up switch for when the airconditioning is turned on.
This is usually located on either the last or the second-to-last vacuum point on the engine side of the plenum from the front towards the rear of the engine. Does it look like some sort of diaphragm?
How about a big hole on the underneath for the block breather?