Hey guys, I was hoping there is someone out there that is just knowledgeable enough to tell me exactly what is wrong with my engine, but if not any pointers are also appreciated...

Just bought my first-ever Maxima & I absolutely love it! only thing is that it seems to be getting a mis-fire. The car never shakes while sitting at a stoplight; there is no rough idling. as soon as I let off the clutch, though, I can feel a heavier-than-normal vibration on the shifter, & can slightly feel it vibrating throughout the car. sometimes the vibrations are there, sometimes they aren't, & sometimes they just come & go second-to-second. When I am giving it gas, sometimes it feels like a lot of power, & other times it feels like a 4-cyl, at which times the vibrations are also present again. occasionally as I am going uphill or something it will be vibrating & then just stop, at which point it feels like you just injected some very weak nitrous or something as it lunges forward /w more power.

So those are the symptoms.. I'm almost sure it's a cylinder mis-fire coming & going... The thing is is that the check engine light is not on. I understand the Ignition coils on these engines were notorious, but would they just come & go like that? and would they not trigger that light? I put 93 octane & some heavy fuel injector cleaner in it a couple tanks ago /w absolutely no effect. I removed & re-installed the ignition coils for all 6 cylinders & the plugs for the front 3 & afterwards it ran seemingly perfect for a day & then started back up again the next day. When I look at the engine @ idle, it is not vibrating or rocking abnormally at all.

OK I think that is all the information I have.. any solutions or pointers are greatly appreciated! Thanks!
Modified by setheroth at 8:39 PM 12/30/2008

Try cleaning the idle air control valve first.