2006 pete with a cat surge or hop

i have a frend with a 2006 pete with 300hp cat engine and auto transmission dump truck .it wants to hop or surge when taking off loaded a nather shop put all new injectors to no avail. no check engine light !!!!!!!! i need help to fix this truck . i,am a auto & light truck mechance ,wheir do you buy pete or cat shop manuls ? is their a scaner to vew date or codes ? wheir to buy or lease ? thanks chuck