What are the possible causes when a truck struggle in acceleration?

Main cause is fuel in your system so your fuel pump might be getting old and not pumping enough fuel into the chainbers, also replace the spark plugs in your vehicle would be a good thing, buy a bottle of fuel injection cleaner, when almost out of fuel in tank pour 2 bootles into the tank and then fuel up, while driving injectors will get cleaned. But like i said main would be your fuel pump my celica did same thing i tryed everything and it kept doing it until fuel pump has been replaced.