2001 Mazda Protege Spark Plugs

A number of things can cause this type of problem. If the plugs are old, then it won't hurt to replace them. However, check for vacuum leaks on the engine and the idle air control valve (IAC). The IAC is responsible for the engine idle speed.

i agree with jacob on this, mazda for some reason has issues with there IAC's.... beware of carbon buildup in the throttle body once you remove the IAC.... carb cleaner, and a small pipe brush should knock it off if you find any.... once you do this, i would disconnect the battery leads, for 30 seconds, and touch them together for another 5 seconds... this will reset your computers adaptive memory. always a good practice when replacing a part that has a direct effect on your engine.... also, check your air boot from the air cleaner to your throttle body, as these are known to get hard/brittle, and crack... that allows an unmetered air leak, as it happens past your MAF sensor.... keep us updated