Another transmission question/issue

[mike_dmt]

I have my 2001 X5 ,4.4 that I've owned for about 8 years. It's been a maintenance hog like no other car I've ever owned. That's saying something, since I'm up to 75+.

Long story short, the Trans Failsafe has popped up, and gone away on restart. The code showed the gear ratio error.

Now, it's "slipping" under acceleration. Except its not. It will lock up and go, but upon pedal induced downshift, it lets go again.

What sort of diagnostics can I do on my own? I have a simple OBDII scanner, no BMW specific scanner though.

I've read a million threads, but they all seem to describe something else than what I'm experiencing.

I've seen drive tests in sport mode recommended, shifting manually. I've heard that it's the solenoids and maybe a small gasket on the valve body.

For the record, I have done a tranny service a bit ago. I checked the fluid level yesterday at temp, and vehicle level etc... It's full. The fluid doesn't smell burned.

I did the solenoid harness a few years ago, due to the temp sensor inside of it failing.

So now I'm wondering if I should put $1000 plus my time and energy into a $2000 car.....

Thanks in advance guys, the help on here over the years has saved me thousands.