Help troubleshoot 904? Slipping at higher RPMs

The Problem appears to be solved. It was a very minor issue. Kinked Transmission line and low fluid. I had installed new Pre-bent Lines and managed to kink one of them somehow at some point. Also the aftermarket Flex Trans dipstick and sheath I used went deeper into the pan than the factory stick so I was miss reading the stick. Replaced the bad section of line, Topped off with Fluid and no more issues (With the trans at least). Put 100 miles on the car today and loved every one of them.

I learned a lot this week with this problem, Mainly I learned who I know I will be going to if I ever need a Trans rebuilt in the future. Thank you Melvin for doing everything possible to help out.