Im having almost the same problem, I bought a 2001 x5 4.4 with tranny problems.

The car will take properly the gears only in manual mode, it will slip or will rev but wont go in first gears.

I change the oil and tranny filter, then the speed sensor and the wiring harness temp sensor.

After changing the parts we rescan the ecu but did not got any more errors.

THe one we had was the 59 stalling speed
plausibility error present.

Appreciate any info before going into changing the tranny.