1997 Chevrolet S10 4.3L Engine Hesitation with P0171, P0174 and P0102 - Post-Fuel Regulator Replacement

I own a 1997 Chevrolet S10 with a 4.3L V6 engine that has developed severe hesitation during acceleration after replacing the fuel pressure regulator due to initial idle issues and leaks. The new regulator, however, appears to be causing ongoing performance problems. After installation, the engine runs poorly when accelerating—especially at full throttle—but performs normally on highways. There is no noticeable stalling or rough idling under normal conditions. Fuel pressure readings are stable at 48–55 psi at idle and increase appropriately during a throttle snap test. I replaced the fuel pump as well, but this did not resolve the issue. All vacuum leaks have been thoroughly checked and ruled out. The mass airflow (MAF) sensor was replaced over a year ago due to prior malfunctions and is no longer suspected as the root cause. I’ve also previously replaced the fuel filter, spark plugs, wires, cap, rotor, and ignition module—none of which were related to this new issue. I currently do not have access to live data, but the engine consistently sets DTCs P0171 (System Too Lean Bank 1), P0174 (System Too Lean Bank 2), and occasionally P0102 (MAF Sensor Low Signal) during driving and idling. My current theory is that the newly installed fuel pressure regulator—specifically a budget brand—is too restrictive, or that the spider injector (part of the fuel rail) may now be malfunctioning. The previous leak condition masked any fuel delivery issues; once the leak stopped, these underlying problems have become apparent. I’m seeking expert input on possible causes and troubleshooting steps for this specific 1997 S10 with these diagnostic codes.