We were haveing a problem with a surge at 1600 to1900RPM. We took it to our dealer (sure treats us well ! )and they did all the tests. There were no codes , fuel presurses were all with in specs . They checked the voltage on the throtle position sensor. It had some strange readings. So they replaced it. Wow! it is like a new truck . Hope this mite help if your truck starts to buck. Oo.