379-427 kPa (55-62 psi)
more than likely you have a weak fuel pump. bringing up the fuel presure will probably take care of your missfire and low power.
A lean condition may result from the fuel pressure being below (55 psi). A lean condition may cause Driveability conditions associated with lean conditions can include hard starting, hesitation, poor driveability, lack of power, surging, and misfiring.
A fuel system that drops more than (2 psi) in 10 minutes after being relieved to (10 psi) indicates a leaking fuel pump check valve.
Fuel pressure that drops-off during acceleration, cruise, or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensorss will stop toggling. The heated oxygen sensor output voltages will drop below 300 mV. The fuel injector pulse width will increase