I have a 2015 QX50 with 87K. Six months ago, I started having engine hesitation when accelerating at a normal speed at no specific gear. Also, if I were to accelerate normally at speeds 50 to 70 MPH, I would sometimes get a slight hesitation with a very unique subtle vibration with low bass sound that is like crossing over a small section of cobblestone. I cleaned the mass airflow sensors, replaced the air intake filters, added a few fuel injector cleaners to my fuel tank, and it slightly helped the problem. I took it to my mechanic but he couldn’t figure it out. I took it to Infiniti and they had it for a week and Infiniti could not figure it out.
I started using using only premium gas and the problem went away until now. I just cleaned the throttle body and added two more fuel injector cleaners without any success. The problem seems to less pronounced when I am in Automanual mode.