Other than a lack of tune-up, dirty TB/intake manifold, & the use of bad gas, what other factors can cause hesitation?

This is highly noticeable not only b/w 2000-3000 rpms, but also on takeoff, so far I've used 2 bottles of Valvoline Sym-Power to clean up the fuel system along w/ fillings of Mobil & Amoco 93, this has helped some, but still very irritating

Btw my SE has just over 85.3K on the odometer, would this also be a factor?

 

Change your fuel filter $7.98 at Pepboys.

Change out Spark Plugs,Use the NGK OEMs(they are the best for Maximas)

Hesitation after that might mean Knock Sensor.