Would a differen intake manifold improve gas mileage

i dont have any of the original parts i bought the truck from a friend of the family for 200 dollars and i dont think it has a diffrent cam shaft but i really dont know much about the truck so i could be wrong i would go ask the guy but he passed away in september and i just lost my job so i cant afford the gas for it so how could i tell if i have a different cam in the motor?