Possible Causes

WARNING: This page is about a different car, the 2003 Mazda MPV and 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

Engine compression low.
Exhaust system leak.
Front HO2S deterioration.
Front HO2S heater malfunction.
Fuel filter clogged or restricted.
Fuel leakage on fuel line between fuel delivery pipe and fuel pump.
Fuel pump malfunction.
Fuel return hose clogged.
Misfire.
Pressure regulator malfunction.
Purge solenoid valve malfunction.
Purge solenoid valve hoses improperly connected.