Could the airbox being loose cause problems?
 

Simple enough, I'm missing the screws on the back, and it's loose, could it cause a 'boost leak' or something of that nature?! THANKS!

Won't cause a boost or vac leak, But your gonna get hot air and worse dirt past your air filter. I change my oil often enough. dont need extra stuff coming down my intake.

I think your problem is the MAF sensor. I watched your video and that seems like the best explanation. Had a similar problem on mine. The airbox couldn't cause that problem, but definitely needs to be fixed.
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Hey badue, do you mean AFM sensor? I don't have a mass air flow kit on my car or anything...

In stock form the MAF (Mass Air Flow also called Vane Air Meter, Air Flow Meter etc.NOT AN AIR/FUEL METER like goes on your dash) sensor is attached to the airbox and has a swinging door inside it that measures airflow. This sensor is restrictive and problematic and the main reason for getting rid of it and going with a hotwire type MAF is to decrease intake air restriction, and the hot-wire MAFs are faster at measuring air flow changes. To use a simple ananlogy the stock MAF operates much like a gun-style electric slot car controller. The swinging door is the trigger. Now, after years in can develop bad spots where the contact isn't making up good, and hence the bad readings at that particular load. This is the most common area for sensor troubles on our cars. The other is the TPS. (Throttle postition sensor)Another common problem that can cause trouble is the plugs getting some corrosion on these two sensors. If you have access to a MAF try swapping and see. Or instead of having to spend money to fix it, go ahead with the MAF upgrade you were planning.