Hey guy in super new to forums and Nissan for that matter! So iv had this 03 g35 for about 6-7 months now absolutely love it been great but about 2 weeks ago my engine light came on and I has a loss in power when full throttle that would come and go and i could here it change exhaust and intake note I read the code it was a p0300! I replaced all the plugs check coil packs put it all back together and same thing I can ease on the throttle and get full power but if I down shift and snap on it has nothing the engine light has stayed off for over 200 km now no codes but still the random lost in power any ideas

 

That's a code for misfiring on all cylinders. Does the CEL flash or just throw that one code? You want to look for something that can affect everything. Your MAF, fuel, or ignition system would be a good place to start and if you can read live data, I would look at your fuel trims and misfire counts.

 

P0300 is for multiple random misfire just means it happen at least 3 cylinder! But it did flash about a week ago cmbut I cleared code and hasn't come back in over 200 300 km and like sometimes I have full power no problems and sometimes it's just a bag

 

Look for something broken, every vacuum line, wiring harnesses at the cam solenoids, phase sensors, exhaust, etc. Intermittent problems that only show at WOT can be a pain in the butt to find but start by looking for something broken. When the engine torques the chassis it could be making a momentary break.