lt1 h/c running super lean
fuel pump
fuel press reg
vacuum leak, broken intake valve
exh leak - did u verify the stock NB O2s reading lean also?
WB O2 sensor failure
Try a different WB O2 sensor?
Always start with fuel press - check fuel press yet?
BTW u have zilch in your profile so u should expect as much for assistance.
Where did u mention anything about a "false lean"? I read something u looked for exh leaks, nothing 'bout a gauge problem. Well i can see theres nothing for me to help with here.
Good luck with your "gauge problem".
Also, a signature that has your vehicle specs (year, make, model, trans type, and mods) will help guys like us troubleshoot your vehicle with you online. All that information is applicable to vague questions like this one.

