maf sensor

[bucknasty]

Im new to this site and this problem is new with my truck so ill fill you in. I have a 2001 chevy silverado 1500hd crew cab with a short bed that has the 6.0l engine in it. about 2 weeks ago my truck couldnt go through the canyon because it was cutting out and when I put the pedal down you could just hear the throttle open and no response. I thought that it was the fuel pump because I had the same kinda issues last year when my fuel pump really did go out. the service engine light came on so I put a code reader on it and it showed up as the mass air flow sensor. I put it off for awhile money issues.. Yesterday I went and got the computer checked again and same thing so I broke down and bought a maf sensor. drove it around and it didnt change one thing. so I disconnected it and drove it around it acted the same way shift points are off, loss of power so I dont think that it is the maf sensor. I emptied the gas tank till it had about an eighth left then I put some injector cleaner gas additive in with a full tank of higher octane gas. That seemed to make a difference, it ran smoother and it didnt shift as hard or take as long to shift. so tomorrow I am going to take the plugs out clean them up and think of some more stuff to clean but if you have any ideas on what else would trigger my service engine light to come on and show its the maf senor i would appreciate your advise. Is there another sensor after the maf sensor before the computer?
thanks for reading this I know it was long!