Possible fuel issues please help
I scored a used EFILive license and cable on eBay and it's been a great investment for troubleshooting and tuning. Only other way to diagnose these engines without a scanner is to throw parts at it until it's fixed.
If you have a manifold-referenced FPR (mounted at the fuel rails, with a return line), then om your calibration the IFR table is required to be the same value all across, not sloped like the stock non-referenced FPR from GM (which is in the tank)...
If you can't get the IFR table modified like this, then disconnect the reference hose like crainholio said and cap it off, and adjust the FPR to obtain 58 psi rail pressure.






