Why does my truck have a hard time starting up?

Could be a bad starter, bad battery, bad alternator, fouled or burned plugs, clogged fuel injectors, dirty fuel filter, bad microchip, or combinations thereof. I'd start by removing the battery cables and cleaning the terminals and cable clamps with a weak solution of vinegar in water, then rinsing them off. Spray with WD40 and reassemble. See if that helps. If it doesn't, go on from there. Remember not to touch any part of the car or the other cable when handle the cables.