Read on another board that the MAP sensor needs to be positioned with the vacuum port facing downward to function correctly.

Is this correct? I've never torn a MAP sensor apart, but I deduced that it had a diaphragm inside and the rest was solid state electronics. Not sure if the position/orientation of the sensor affects operation, hoping someone here can answer this question.

 

Never thought about it before, but I've never seen one that wasn't positioned as you said. There may be something to that.