i have a 90 ford f350 dually with 7.3 no turbo. when i am on the gas lightly between 25 and 45 the rpm will rev up and down but if i am on the gas hard it goesnt do it just had transmisssion rebuilt. can i get some ideas

 

might be picking up air in the fuel ???? ummm..... maybe you have a band thats slipping... would have the trans guy check it out before ya get too far in it withthe cash..... can cost big time........