Are you using a trustable wideband to get your afrs? Even the stock 02 should show 11.XX under boosted conditions during WOT. A decent intake leak pre turbo can cause AFR's to skyrocket during a pull.
If the pump is in good condition and your not seeing any misfires from a faulty injector its probably not fuel related mechanically at a stage 2 level.
Did you install the fuel pump because of the lean issue or just as a replacement? If you replaced it during modification and are running into a lean condition under boost you should make sure the pump is seated properly in the housing and it might not be able to keep up if its not sealed up in the basket.
Hope that helps.
oh btw what modifications are on the car?
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