i currently have an 06 5AT with 1200mi. something i noticed was that whenever i am cruising at a certain speed and i either let off the pedal for a second or two or brake and then get back on the pedal, the rpm barely begins to rise after its initial drop unless i floor it which eventually gets it up. so i dont accelerate as fast i could either. i wasnt too sure of whether or not this is normal considering i never encountered this with any other cars.

another thing i noticed was that i get a shaking of the car when i am in traffic and i encounter the rpm issue. when i cruise at about 20-40mph and sometimes up to 50 and the rpm is at around 2000 or a little below, it shakes up and down. i went to the dealer to check my wheel alignment and they said it was off and i got it adjusted, but i still encounter this problem although not as much and the shaking happens to a lesser extent.

gyea, i need some help

 

It does not go instantly into a lower gear to make up for the slower speed. It is not that reactive. Some other autos seem to respond to every little change constantly changing gear to keep the RPMs close to same. But they probably do that with some risk of faster wear too. (It would seem, I don't really know). Plus, typically they don't have as good a manual mode feature.
Maybe Infiniti/Nissan thinks with the amount of torque available it's not an issue. You can always slip over to manual model and bring it down a gear for more power without having mash the accelerator.
As far as the shaking, I'm not really sure what is happening there, but does not sound normal. A tech should drive it with you in the car .