The gas pedal could be difficult to push down for a few reasons. One reason that it could be hard is due to a pinch in the cable. It could also be an issue with the gas linkage.
Well, what noise is it making? There's lots of "funny" noises which trucks can make. If you're not sure, take it to a mechanic and have them give it a once over.
There might not be something wrong with the gas pedal, but with your knee.
push the gas pedal really hard
push the gas pedal
push on the gas pedal, man!!
is it sputtering bucking when you push the pedal? what year 6 do you have?
Chances are you have a bad ball bearing in your wheel hub and you need to change it out
Push the gas pedal about halfway down, then release it real quick.
You forgot to release the parking brake.
I guess you turn on you car, leave it in neutral, and push on the gas pedal repeatedly.
going by experience that is most likely ign or an egr problem