5.3 Shuttle Shifting

I have an 00 Silverado z71 4x4 with 115,000 on it. I have been having this problem for a while now. It seems to be getting worse. When driving down the highway or up\down a hill at a constant speed it feels like it is trying to shift but it is already in o\d or drive. There is no climb in the rpm's that are noticeable by the gauge. I have had injectors cleaned, trans flushed, screen replaced, fuel regulator, egr valve, air cleaner, differential oil changed. I have had it to dealership and it was scanned and it didnt have a faults in the system. This is really getting old. Any help would be appreciated.

I recommend pulling the negative battery cable for at least 15mins. this will reset the computer, hence fix your almost shifting problem.

please tell me if that works. i have the same problem.