2001 GMC Sierra 1500C Pick-Up Truck Gas Pedal Sticking

I have a problem with my 2001 GMC Sierra 1500C Pick-Up Truck.  This has been going on for 7 months and nobody can find what the problem is.  This happens in any type of weather and at any given time.  The gas pedal is sticking.  It's doesn't stick and stay down when I would accelerate in someone, it sticks as I am accelerating and pops back fine when I go to press it again, I can feel resistance.   At first I can feel it sticking a little bit and with each acceleration is sticks a little more and then feels like it wants to die out.  It dies out sometimes after it starts running rough.  Sometimes the accelerator won't go down at all no matter how hard I press the gas pedal and I have to coast to the side of the road and wait for it to work again.  Once it starts working, the pedal is fine.  The fuel pump was replaced, so it's not that.  This is happening an average of once every three weeks.  It starts up every time if it does die out.  Any suggestions?