Hello.
I am owner of 350z 5speed automatic since 4years, but just noticed strange thing. I have no idea if earlier was the same or not.
When I drive car in manual mode on 5th or 4th gear and I fully open the throttle car start to accalerate slowly ( its normal, low rpms high gear) but something strange happens about 3750 rpm, RPMs drop a little (about 100 ?), of course throttle is still fully opened , after that car accelerate normally and it doesn't happen with higher rpms... also in lower gears its difficult to see because everything happens so fast. No service engine soon light, no error code, engine generally in good shape, good power, I have 80k miles on my car. Here is youtube video wich shows my problem: https://www.youtube.com/watch?v=cg0C...ature=youtu.be
Its maybe an issue with torque converter ? Could anyone with 5speedautomatic check how his car accelerate when 5th or 4th gear is locked with manual mode ?

 

Could be a lock-up torque converter locking up. In which case it's normal.