I hope this did not show up after a switch to a synthetic tranny fluid. Some synthetics are so slippery they do not allow the Sprague Rollers to grip the race and drive the output bell of the OD.

If the above is not applicable, and you are slipping in gears one through 4, and your clutch has proper free play, there are two areas to be concerned with.

The Sprague(One way)clutch, which requires replacement of the Sprague unit.

A hydraulic control problem which varies as to cure whether you have a D or J type OD.

To tell the difference, D has single wire to solenoid on right side of auto, J has 2 wires to solenoid on left side of vehicle.

If only in OD mode, does synthetic fluid use apply? Then the cone clutch or hydraulic controls are at fault. You would have to provide me with more specificc info to have me guide you through the diagnostics.

This should be done offline so as not to waste bandwith on the board with stuff that probably does not apply to the cure.

Duane