I have a 1989 K1500 with the 350 engine. Auto transmission but model is unknown. Here is my issue.

From a stop when selecting overdrive the truck will not move. It simply will rev as if it were in neutral. If you select drive it will then move. It will drive fine. If you go over 30-35 mph you can select overdrive and it will go fine.

If you slow down to turn and you are in overdrive, it will again act like neutral. You need to accelerate to 30-35 in order to shift back into overdrive.

Anyone have any ideas? I have searched a bit online and had no luck.

Thanks in advance.