Just cant figure it out
 

I own a 2000 Frontier and one day it began gasping for fuel at speeds in excess of 50 mph. A couple days later it began doing it in idle and when you first crack the throttle. I went in and changed the plugs,wires,cap,rotor,air filter,and fuel filter and it still is doing the same thing.
The vehicle has over 120,000 miles and has more or less been up to date on servicing.

Im wondering if there is something else that could be affecting the fuel getting in to the motor. anyway Im in need of some advice because I just cant figure it out. I would really appreciate any good advice. Dave email me- tualoli@yahoo.com