Possible Causes

WARNING: This page is about a different car, the 2003 Mazda Protege5 and 2003 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.

Fuel injector malfunction.
Low engine compression.
Related connector, terminal or wiring malfunction.
Secondary ignition system malfunction.
Spark plug malfunction.
Vacuum leak in intake-air system between dynamic chamber and cylinder head.