GM / General Motors: Engine Mis-Fire = Better Shifting???

I'll keep this as short and sweet as possible!

I have been dealing with a hard 1-2 upshift for months on end now.
I've had the transmission serviced along with a New adjustable Vacuum
Modulator installed, but that did not help at all. The transmission
is a 440t4.

Recently, I had a spark plug wire rub-up against my exhaust manifold,
split open, and cause a cylinder misfire. It happened while driving.
The car was still driveable, so I drove it to my mechanics to figure
out what was going on.

On the way there, while driving with the misfire, I noticed that my
1-2 upshift had some how cured itself, and the transmission was now
shifting perfectly? I actually drove it for a little longer than it
would have taken me, just to make sure I wasn't losing my mind, and
not once did it make the annoying slip/pull/bang that it normally does
when going into 2nd gear.

Some one on another Forum stated that it could possibly be due to a
bad Vacuum Modulator. They stated that a misfire causes a loss of
vacuum, and that I should try adjusting my modulator by turning the
"T" inside it counter clockwise, which will basically lower the
vacuum, and do the same thing as the misfire did?

Does this make any sense at all?

Oh yeah, one other thing, if I let almost completely OFF the gas pedal
JUST before it shifts into 2nd(and therefore increasing engine
vacuum), I can usually get it to shift into 2nd without the usual
"bang".

THANKS