Weird, sudden AFR issue Proform 750cfm!

I am running vacuum advance off the full vacuum port on the front.
I understand the tuning advice better now, and I am working my way there. Great advice and very much appreciated!
The thing is, even with all that needing done, I had the fuel curve pretty decent, and then ALL OF THE SUDDEN, something changed!

Accelerator pump? Too tight or maladjusted or a diaphragm issue, from something I did and didn't notice one of the 20 times I had this carb apart the last few weeks?
Unfortunately, I have no way to see what if it is dribbling under vacuum while driving. I do feel like this is the most likely culprit.Is there some other way to test it?

Trash in the carb? I THINK I eliminated that probability yesterday. Did I dislodge something checking restrictor sizes? Could I have been tuning to a blocked passage that is no longer blocked, allowing more fuel now?

O2 sensor, or meter?
How would it read accurate at idle, then go wild under flow?


I will order the blanks and fix the IFR and emulsion. I have a whole other carb to fix after I get this one sorted out, also a Proform 750, but a race model, which brings me to my next question.
Which rebuild kits are you guys using that come with the more ethanol resistant parts like the accelarator pump diaphragms?

Thank you all for the input!!