(new) Fuel Pump dying?

[Nathan Engelbert]

Car is an 89 90q.

A little over a month ago, I replaced my buzzing FP with a new pierburg FP
from Blau.  At the time, I also replaced the fuel filter at the same time.
Didn't do the accumulator though, probably should have.  Ever since the
replacement, the new FP has been making noise, not a buzz, but more of a
tone around 400-500 Hz.  This is heard well from inside the car at idle, and
can also be heard outside the car.

Last night, I finally fixed a vacuum leak in the ISV circuit (plastic
fitting back by cyl 5 that goes down to engine) that had cracked at the
point where the hose goes down to the engine.  I decided to run through the
gears on the way home from bowling league on Lake Shore Drive in Chicago,
and in second gear the car bucked hard twice over 4500 rpm in second.  I let
off the throttle, and continued my drive.  The rest of the drive back, the
throttle response and power under increasing throttle application seems to
have decreased significantly.

With the vacuum leak, I had been having some warm start issues, which are
now solved.  BUT, after replacement of the vacuum coupling, I adjusted the
idle position screw on the throttle body to bring the idle down to 850 rpm,
as it was at 1100.

Is my fuel pump going bad/bad from the start?  Have i screwed something else
up?  What is the position of the screw on the TB on other owners' cars (how
many threads showing on either side)?

TIA,

Nathan Engelbert
89 90q