A Question About A Problem My GMC Is Having...

[Narkoleptik]

Ok, for the last couple of days, my truck has been having a rough time taking off at the lights... It used to be that hitting the gas meant that the truck would immediately leave the line and run smoothly... Now, when I step on the gas, (not hard mind you) it takes a few seconds for it to speed up to what it used to be like. It kinda seems to struggle when started at an upward angle (IE a light on an overpass) Almost like it is wanting to shut itself off... MY father says it might be a problem with the fuel pump and I haven't been able to replace it with a new one, was wonder what most of you thought as well? Perhaps Tranny problems? (HOPE NOT)

Thanks in advance for your input.