Presume you checked the OVPR ?
They usually are out of spec on C/O%.
Try running it to warm...check the O2 reading with O2 diconnected ...should read around 0.200vdc to 0.750vdc on a DVM.

Then you can trim the C/O% to about 0.500vdc or just lower.
If you open the air flap as you open throttle does it rev okay?


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