Lean Condition

[LATEXFRIEK]

Hi, 87 Chevy V-20 w350 4x4, throwing a code 44. O2 sensor exhaust lean condition. I did a search and tried just about everything I could find in other similar posts. I know a lot of things can throw that code, I'm just hoping to narrow it down a bit. Ok, here goes..

First of all I have a scantool with real time data and maybe we can narrow it down this way.
O2 sensor is fluctuating back and forth between rich and lean. Is this normal? If so why the lean condition?
O2 sensor is new and connections are good as far as I can tell.
BLM is sometimes 128, 133, 134. (I need a better explanation on this and what it affects)
I unplugged map sensor while running. No change in O2 sensor function.
Injectors seem to be squirting evenly.
New fuel pump, filter.
New temp sensor.
Cleaned IAC.
EGR is recent.
Tested for vacuum leaks with carb cleaner and no change in idle.
I was reading a little about the air injection system. Correct me if I am wrong. In closed loop (when cold?) NO air is supposed to be injected into the exhaust? Can I test that by taking off the hose from the valve going to the exhaust while cold and see if there is air coming out? What are your thoughts? Thanks