My brother just purchased this truck for a 2nd vehicle an it runs great but when you are driving an get around 45-50mph it starts to hesitate an sputter a little . I was thinking it could be the catalytic converter or maybe a bad fuel filter anyone got any ideas?

 

sounds like it could be fuel ! the fuel filter would be a good guess or the fuel regulator !

 

It could be so many different things. I would start with a look at the spark plugs, wires and coil pack.