misfire: injectors or plugs?

'01 w/ ~93K miles

running rough lately, and actually threw a "cylinder 4 misfire" code the other day (so says the free check at autozone).

was thinking of replacing plugs (would be the 2nd time: once @ 35K; "schedule B" says i shoulda done again at 60 and 90), but autozone guy suggested it could be injectors.

last fill-up i went ahead and sprung for the "additech" infusion which purports to clean injectors.

thoughts?

thanks in advance.

You should at least pull the #4 plug and see what it looks like. Should be a very light tan with proper gap (.035"). If gap is getting up to .045", I'd replace them. What about your distributor cap, rotor and wires. You could mist your stuff at night and look for arcing. If this stuff is all good, try swapping the injectors and see of the code moves to a different cylinder. If you disconnect the plug on the #4 injector, does it run a lot rougher, it should. If not, that injector isn't working.

winterbeater said:

You should at least pull the #4 plug and see what it looks like. Should be a very light tan with proper gap (.035"). If gap is getting up to .045", I'd replace them. What about your distributor cap, rotor and wires. You could mist your stuff at night and look for arcing. If this stuff is all good, try swapping the injectors and see of the code moves to a different cylinder. If you disconnect the plug on the #4 injector, does it run a lot rougher, it should. If not, that injector isn't working.

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I don't believe an 01 has a cap or rotor.

Right you are!