More Data

If BLM and INT are always at 128 even when driving then
it sounds like it's not leaving closed loop. If BLM/INTs
are below 128 that means that the engine is running rich
and the computer is leaning the fuel mixture to
compensate. If it is above 128 then it means the engine
is running lean and adding fuel to compensate. IIRC it
can swing between 108 and 140 or something like that.

BLM is the long-term multiplier and INT is the short
term. INT will usually change constantly but BLM doesn't
change as quickly. These only change once in closed loop
(engine fully warmed up).

If you're running rich all the time it can foul the O2
sensor quickly so the computer might think it's lean when
it's not, adding fuel and running rich. Also some say
that different brands of O2 sensors have slightly
different signals so it's best to buy a Delphi sensor.

If you were to unplug the O2 sensor and it didn't run as
rich (although it would throw a code); that would
probably indicate an issue with the O2 sensor.

If it's not leaving open-loop that's another issue
because the computer won't use the O2 sensor to
compensate for undesired air/fuels until it enters
closed-loop. To enter closed loop it usually needs to
reach a certain temperature and needs to be running for a
set amount of time (unsure of the specifics).

Hope that's helpful.

Sounds like it might be running slightly rich but the
computer is able to compensate. Does it still run rich
once fully warmed up? Try seeing how it runs with the O2
unplugged.

O2 voltage varies so quickly on my engine I only use the
BLMs to get an idea of what the air/fuels are actually
like.