I never could get my bike to run great with the TBS needles.
I just use the stock needles with 2 shims.
but that was mostly mid range.
with the bottom end problem it sound more like vacume or
to much richness.
start the bike up and just let it idle for a while .
do not touch the throttle.
careful not to let it get to hot.
then shut it off and check the plugs .
this will give you a good reading of the idle.
if you ride or rev the throttle you do not get a
good idle reading from the plugs.
just an reading from the full range.
