Hi guys. I'm having issues with my transmission in my 1992 SC400. It shifts smoothly for the first 15 minutes or so of driving. It starts acting up when the car is all the way warmed up. No lights on the dash so I assume no codes are being thrown. When I shift into drive after it's warmed up it jerks and the rpm's fall. Acceleration is jerky and uneven, and the car barely wants to move. If I let it cool down then it shifts just fine. Any ideas? I've already changed about half of the transmission fluid with new fluid, and it only has 103,000 miles on it.

 

What did the fluid look like? Why did you change it in the first place?

 

Fluid was dark, purple-ish brown. Just bought the car and wanted to refresh all the fluids.

 

It seems to me that it could be some sort of sensor problem. Are there any common failures that could cause this? I have general experience with cars but this is my first Toyota product, and I'm not aware of all the nuances that they have.