Thottle issue?

[jcmagone]

Over the weekend I pulled my 5ver and loaded atv trailer up a pass in Utah that is fairly steep. I noticed when the truck slowed up and downshifted that when the throttle was pressed all of the way to the floor that I could let it up about a half inch and push it back down and get more rev and go out of the motor. It would last after pressing the petal back to the floor for about 3 or 4 seconds and then would die back down. If let up again and pressed down again I would regain the rpms for another 3 or 4 seconds. I don’t know if there is something wrong or if this is normal. It seemed the extra increase in rpms was what I needed to keep pulling at a respectable speed. The truck seems to run pretty good other than when it is first started it has a rough idle but smoothes out after a few or when the pedal is pressed. Any thoughts or ideas?