Just an idea... I think should be enough to check the valley pan opening, remove the EGR valve and check through the passages for that, instead remove the full intake just for checking.

and I know this is off topic, but preffer post in public just in case I'm wrong about your car wire brackets setup, but this is mine ( post 73 Big Block, in this case 74 Charger ):




With a Charger born in Chrysler assembly plant in Valencia, Venezuela