With the new numbers, The Wallace predicts ~132 psi, and the new V/P is 106, better than 99, but still pretty weak. We'll see how your Compression test compares.
Average 133
I'd say the Wallace is right on target
And I'd say there's your low-rpm power problem.
Now, what to do about it.....
#7 cylinder is ~10% down from the average, but #6/8 are 5% higher. So Ima thinking you need to do a LeakDown test, cuz something is goin' on in there, in it can't be good. That is what I would do.
Looking at the plugs, what Timings are you running? Looks a hair lean to me, and a hair hot. @yellow rose ?
