Pulled everything apart tonight and did a close inspection. All visible vacuum lines appeared to be properly installed and un-damaged. I did notice a couple of things about the intake though:
1. The Airaid rests right on the radiator hose, which gets hot enough to slightly deform the tube over time. Not by much, but it's noticeable. I doubt it does much of anything to impact the performance of the tube itself...but once your truck is up to operating temp, that heat is transferred directly to the tube. I know "heat soak" issues as it relates to intake tubes have been proven several times over to not actually be an "issue" since the air moves so fast through the tube, but I still wonder about it in the back of my mind.
2. Upon removing the rubber collar holding the tube to the throttle body and looking at it closely under a shop light, I saw a thin layer of dirt built up in the area where the tube sits in the collar. That has to be where the extra air is leaking in. The design of the collar sucks...it's essentially a hose coupler with a ridge in the middle to separate the aluminum throttle body from the plastic tube, but what it really needs is a recess molded into it right next to the ridge on the intake tube side that will allow the lip on the tube to fit into it more securely. I thoroughly cleaned all of the surfaces and gave them a liberal coating of hairspray as suggested by Strokinpower (my wife's Volumaxx to the rescue), disconnected the battery (yet again...sigh), cranked all of the worm clamps down as tight as I possibly could get them, and let the truck cool down for a few hours. The result? No stumbling upon startup a few minutes ago. Progress!!
I didn't drive it yet so the real test will come tomorrow. Also, it seems to stumble the worst during startup after it's been sitting all night and the block is stone cold. When I start it up tomorrow morning, that will be a big indicator as to whether or not this issue is solved, then the next few days will tell the tale. I have to wonder if replacing the POS rubber collar with a nice silicone coupler would solve this issue permanently...
Another update to follow in 48 hours or so.