[blue62]

Colacharlie.

Your vacuum readings are low. Ideal would be 17-21 in.hg
I see lots of oil dirt residue on the AOS tubes and other parts of the engine.
So that tells me that you have minor vacuum leaks at the connections and or tubes themselves.
Another common place for a vacuum leak is the oil fill tube that runs from the trunk to the engine. It can rub the edge of the body where it passes into the engine bay. (hope that makes sense).
These are closed system engines with crankcase vacuum rather then pressure.
So anytime you see oil or oil dirt residue on the upper engine area, around the intake, or the AOS you have vacuum leaks.

If your vacuum gauge needle is rock steady when you test then there is most likely no valve train issues. I think your low vacuum is all down to minor vacuum leaks.

With the way your car acts in the video and that fact that it is smooth at any RPM until you give it more gas. Vacuum leaks don't typically act that way once your at around 2000-3000 RPM so I think it may be more of a fuel delivery problem rather then an air metering problem. Low fuel pressure or low volume. Once you step on the throttle there is a momentary lag in the fuel systems ability to meet demand. thats the theory anyway.
Although a faulty MAF (which you have changed out so it is most likely good) or a faulty Throttle position sensor (which has not been tested) could have the same affect.

A confusing thing to me is that you have no misfire codes and your Durametric shows no misfires. Are you certain it is misfiring????

I would do a fuel pressure test at the rail (which I see your preparing to do) next.
There is a spec. for key on engine off. and a spec. for engine running.
If you need those spec. let me know I will look them up.

Sorry I do not know the thread size for the fuel rail test valve.
unbelievable that the sent you a fuel test kit without correct fittings.