I have a 96 ram 3500 original owner. The original trans was rebuilt in 2012 to include billet input and output shafts and a triple plate torque converter along with a few other goodies. All has been well until recently. Now when the trans is cold in the morning it shifts perfect however when it gets to operating temp it doesn't want to shift unless you let off the fuel pedal, dropping the RPM, and it shifts. I have done the fluid and filter change and did not make a difference. ANY IDEAS?????
Thanks for the help

 

Is that on all shifts, or only certain shifts?

 

On all shifts
Thanks

 

Did you check the valve body bolts for tightness?
The reason is that as the fluid gets thinner leakage gets more evident- and if you have a leak from the governor circuit it will do what you describe.