I think I found the main problem with the transmission.
 

Hello everyone just wanted to give everyone an update on my 00 Volvo S80 T6.

If you've seen some of my other posts you probably saw that I was having some problems with the transmission. One of the problems was the torque converter clutch engaging in and out . Well with further research I also found that I had a code for the brake pedal position sensor .
So I figured that if the sensor was bad it could cause some confusion with the transmission.
So I disconnected the brake pedal position sensor and now everything is shifting great. I will keep you posted as I need to do more driving to make sure.
But anyway does this make sense? Any input will be helpful.
Thank you!

Update
 

Well did some more driving today and the problem is solved. No slipping at all! And my gas mileage has gone up. I wish I had disconnected the sensor 9 months ago. ( I've had the brake pedal position sensor error since I bought it ) . I may have had a unique situation here. But glad it's finally fixed. Now should I replace that sensor or leave it disconnected?
Thank you.