Have an annoying part throttle lean that I cannot tune out. Motor is a 5.3 LS motor bored out .5mm with flat top pistons, LS1 cam and a 670 Vac Sec Brawler carb. Vacuum 22/18 inHg in gear. 1/2 inch spacer so my carb will clear the MSD box bolted to the manifold. With a the idle screws 1/2 turn out, idle is around 13 AFR. When I'm at cruise, 35 MPH around 1000 RPM, AFR is around 14-15. AFR drops as throttle increases. WOT is really rich.

Current setup on the carb:
Power valve - 8.5/Stock 6.5. Had a terrible bog with the stock size.
Jets - 70/70
IFR - .03/.03
IAB - .063/.063, Stock is .07/.07
HAB - .035/.035, Stock is .028/.028. I raised these to lean out the upper part of the fuel curve.

Changing the air bleeds didn't make much a difference. I tried dropping the idle feed restrictors but that created another issue. I've taken the idle air bleeds from 63-75 and not seen any change in the difference in AFRs from idle to part throttle cruise. How do I tune out the part throttle lean? Thanks.