At speeds 40-60, when climbing a grade, the transmission will try to kick down to the next step down - probably out of OD. If you quickly lift your foot off of the accelerator it will make the shift but will only jerk and try but not complete the kickdown.
This sounds like a simple TPS (Throttle Position Sensor) symptom but resumed after replacing it. OEM sensor was used.

This just started about a month ago as it approached the 200000 mile marker. Shifting otherwise is smooth as glass and kickdowns at low speed are normal. It is also smooth when forcing it as stated above.... a quick up and down with the accelerator punch.

Any suggestions...

Thanks

 

Wouldn't think TPS issue

What happens if you turn OD OFF, at speed?
Does it downshift shift to 4th OK?

More likely to be an issue with OD drum or band, maybe solenoid/valve

Has OD OFF light ever Flashed, that can mean a transmission code is set, CEL doesn't come on for this since its a transmission code not an engine code

 

I am really watching it - it is not severe - YET. Also trying to remember to press the OD button to see what gear it reverts to. That transmission has been so smooth, it is difficult to decipher which gear is which.

New thought train --I have not had the opportunity to refer to the maintenance schedule for the Transmisson. We had a Honda Civic that experienced the same type of shifting pattern....it was right at the transmission service interval for it. Have not been a long time owner of this truck, I have no service info on the transmisson and doubt it was ever changed.... The oil is not bright but not burned... Not inexpensive but would be in the best interest of the transmission to give it a taste of fresh oil. 10+ qts.

 

Usually about 3 quarts stay in torque converter, so won't take full 10 quarts