Running a bit rough. Doesn't stall, but when stepping on the gas it will sputter on 2001 Mazda B3000

Check engine light comes on. Got that checked. Code meant a problem with #3 cylinder. Replaced that spark plug and got a new set of wires put in. Yet the sputtering remains. Not sure what to try next. Even check the air in-flow and it looks clean. What do you think?

Asked by for the 2001 Mazda B3000
What did the spark plug that you replaced look like? That info would help point a direction , if indeed it was a problem (presume DTC P0303).
The spark plug looked used\ slightly blacken.
1 more answer
possible injector?