1227727 $8D corvette 1991

Hello everyone,

I've been trying to adjust the settings for a new 383 engine that runs mild cam and larger intake runners, and there seems to be an issue I don't understand. At 1000-1200 rpm and 70-85kPa the INT and BLM are both below 118 but the O2 reads low 100, even 40mV. I also have an AFR WB on the right bank that reads around 16.5 in these situations. In the TPro I have created an NB O2 lookup table to convert the O2 mV's to AFR and it is pretty close to what I see on the WB. Initially I thought the right bank was leaner but looks like when the right bank is lean the left bank is lean as well. The spark plugs also look the same... both banks. The lean condition is also confirmed by misfiring. The target AFR was 12.5 in that region. Why does't the ECM add more fuel when it sees low voltage on the O2 and instead it substracts it?
I've also set the stoichiometric ratio to 14 for E10 fuel or even 13.2, and while it displays target AFR at idle at 14 or 13.2 I don't see that on WB, it is still lean on idle 15-16.5. I've tried Open Loop mode below a set rpm and that way I managed to lower the AFR, but I still don't understand why I can't do it in Closed Loop
PS. I've checked an old log of the stock l98 and apparently there was the same lean condition on low load low rpm when setting the car in motion. Now with the more aggressive cam it kind of stumbles a bit, you need an rpm of 1200 to start off.
PS. Doing some AE mods, I guess that’s what I need to modify