ISSUE SOLVED: Finally spent the money on a smoke machine and well worth every penny ($150 w/smoke juice). After a year of running around with a check engine light on for a secondary air injection code, I immediately located what was causing my issue as soon as I hooked it up. It was the brake booster vacuum line connection that connects at the back of the manifold. There is a little plastic hose line connector that goes inside the manifold hole. I purchased mine here on Pelican. The original one was leaking like a civ. The one-way valve on the line may have also been plugged so I replaced the entire line as well. The smoke machine is the hero here on this one. I should have bought it a year ago.

It's crazy because I paid a garage to provide a smoke test about a year ago and he found nothing. I think this story shows it pays to do it yourself.