Possible Causes

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Fuel filter clogged or restricted
Fuel injector malfunction
Fuel leakage on fuel line from fuel delivery pipe and fuel pump
Fuel pump malfunction
Fuel return hose clogged
Insufficient compression
Leakage in exhaust system
MAF/IAT sensor malfunction
Misfire
PCM malfunction
Pressure regulator malfunction
Right or left front HO2S deterioration
Right or left front HO2S heater malfunction
Variable valve timing control system improper operation