Hi guys, I bought my v36 G35x Sedan (with the vq35HR) back in June with 95k, and am now taking it into the winter for the first time. Recently ive been noticing this hesitation upon hitting the gas at highway speeds when the revs aren't too high. It happens in D,DS,and manumatic, VDC on/off has no effect either. When im in regular D mode and driving anywhere from 30mph up and proceed to hit the gas(as if to pass someone), the RPMs immediately drop ~200 rpm, and then instantly bounce back to where they should have been and continue accelerating as if nothing happened. It results in this weird jolt in the car when I begin to accelerate moderately. Its easy for me to replicate the problem in manumatic if I put the car in a higher gear with the intentions of cruising and not ripping it. When the rpms aren't way high ready for instant throttle response, I get the jolt. I attached a video I took of it below. Note that in the video, almost right after the jolt occurs Im letting off the gas in an attempt to get as many shots of it as possible. Had I not let off the gas, rpm would have dropped, came back up, and kept climbing.

Some other context: I also recently had the alternator go out on me, which I replaced with a remanufactured one from auto zone. The remanufactured one ended up being just as bad as the first one, so I exchanged it for a duralast gold brand new alternator. The new one seemed to run great, but I did notice a weird idle randomly at points. Usually after a short drive, if I go to just sit in park, voltage meter shows voltage surging around with increments of .2-.3; Ex: 13.2->12.9->13.3, and rpms dip with each surge. Since rpms are dipping and volts are fluctuating all of the vehicles electronics flicker with the surge as well. Not sure if this rough idle is related to the alternator or possibly the same thing causing the RPM dip (clogged fuel injectors, dirty TBs, bad spark plugs?)


TL;DR:
2007 G35x Sedan rpms initially drop when hitting the gas moderately

 

Did you ever figure this out?