I have a 2003 350z and lately its been acting a little weird and ses light came up and I troubleshoot it to p0300 random misfire so I changed all the spark plugs a few of the old ones looked like they were running lean but after changing the plugs problem went away and 3 or 4 days later it came back could this be bad MAF coil packs should I replace the coil boots o2 sensor? any help would be much appreciated!! thanks

 

Start by disconnect the coil leads one-by-one and listen for a change, hopefully you can narrow down if there is an intermittent culprit(s) (the bad one(s) wont cause any change in engine note).

Used coil packs are easy to find on ebay, Ive had two go on me, replaced with OEM used with no issues, though my codes have always been cylinder-specific. I now keep spares on-hand as its just too easy a fix to let it take you down at the track.

Pay particular mind to the condition of the wires/connectors, as this can also be why the problem went away temporarily.

 

This^ x1000

Also keep in mind that on occasions the cam pos sensors can case missfires and or complete stalls if old, but begin with the spark plugs/ Coil packs as described above.

 

that's the funny thig I did that last night I probably got to one cylinder and before anything I unplugged it and then wanted to see what it was gunna act like if I started it so plugged it back in and started it and it was completely fine..... so lame lol

 

that's the funny thig I did that last night I probably got to one cylinder and before anything I unplugged it and then wanted to see what it was gunna act like if I started it so plugged it back in and started it and it was completely fine..... so lame lol