This has boggled my mind and any suggestion would be helpful..

I have 2008 G35Awd and after doing an ECM reset by disconnecting battery for some time and when I take the car for a drive and when hitting the throttle, the engine would be cutting off power like it was running out of fuel or misfiring. This would only.last for several accelertuon attempts and then the hesitation would disappear....the hesitation would decrease slightly with each acceleration attempt till it be completely gone after 10 min of relearn driving....this is my 3rd G35 and none of the other cars would behave like that....is this something wrong with programming I wonder?

 

Starting with a cleared ECM, the system has to relearn and adopt to your driving habits. It is normal for performance to be different until the ECM has fully reset.

 

With my 2004 G, when I installed a new battery first of the year, and the following morning when I went to start the car, it didn't want to start. After cranking it over on and off for probably a minute or so, it would finally stumble then stall after a few seconds. Did that a few times. Finally after holding the accelerator pedal WOT and cranking, it finally fired and I was able to keep it running by blipping the pedal. After a minute the idle cleared up, it even puffed a little cloud of blue smoke when it finally lit off, probably from cranking the snot out of it!
After driving the car for ~20 minutes it was back to running great, like normal. I've reset the ecu with Datascan 2 three times since, none of those times did this happen.

I would guess that the base fuel table for these cars is lean, maybe due to in Japan they have high air temps and really high humidity, thus leaner fuel trims required. That hard start I experienced was in early January, so winter time. That only makes the base fuel mixture even leaner!