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2006 Infiniti FX35 has new coil packs and plugs, still stutters

after replacing ALL 6 coil packs and spark plugs car still sounds/drives weird like its gonna die? Like a studder when it shifts? Im thinking maybe the o2 sensors… also on the ps sounds like my catalytic converter has something broken and rattling? If anyone has these same problems or similar or even a solution please let me know. thanks

Is the check engine light on? Have you had the codes read? Do you understand what those codes mean? Or are you just blindly changing parts until that fixes it? If you are just blindly changing parts, it is going to get VERY expensive and the problem still won’t be fixed.

Post the codes your car has set. You can get them read at most auto parts stores for free. Post the actual codes in the format “P1234” and we’ll try and help.

a prior misfire could have damaged the cats and now there are other issues. could be a VVT timing issue. a bad EGR issue. a vacuum leak. low/uneven cyl compression issue and so on.
all the coils were bad? and the pcm controls coil firing?

O2 sensor problems causing this symptom are uncommon, but sometimes do occur. The O2 sensors aren’t used for the first few minutes after the engine is started. If it has the same problems right after starting the engine, unlikely to be O2 sensors.

If the stuttering occurs mostly on acceleration, consider an exhaust restriction or fuel pressure problem. If mostly at idle and lower speeds consider an overly lean mixture or misfiring.