My parents own a 2000 f150 4x4 5.4L auto that just turned 100k. Transmission started doing something weird recently. The rpms in 1st gear will just continue to climb until you let off the gas pedal a little bit then it shifts into 2nd. It only did it for a few days but now seems to be back to normal. Any ideas, fluid level is good and still nice in color.

 

How long since the fluid was changed?

 

Not sure on the history. They purchased it from the dealership at around 65k. I'm sure its due for a change. They're taking it in this week to do so and see if it helps. It only happened for those few days then went away. Seems odd

 

sounds as if some trash casued a valve to stick, then it freed up.