Most stock motors Ive seen pull 16"-19" of vac..
What breather set-up do you have on the car right now? You should have the closed cap on the oil fill, and I think
Vortech still supplies the hose with the filter that goes to the airbox. Make sure all the spark plug wires are connected tight, the ,035" gap shouldnt have been an issue. They are standard core plugs not platnium right?
Try re-setting the EEC, it will take a few mins for it to learn how to idle. Disconnect the battery for 10 mins, then hook everything back up and let it idle, turn the heat on as well, go drive it. Resetting the EEC will not hurt however your vac reading is still low and is suspect to me... Check the vac fittings on the rear underside of the intake, the hose going to the FPR.
IF the car ran fine before the blower install it is definitly from something you touched or moved during the install, retrace your steps and triple check the connections, make sure the MAF harness is plugged tight and the meter is installed in the proper direction.