Seems like my green pet doesn't really intend stop biting my wallet.
Earlier this year I wrote about my transmission change, which I was able get done rather economically. But since that time, and increasing now, the car has an enormous creeping torque when stopped. I really have to step on the brake quite hard to stop it from low speed or to hold it in place at the red lights. At least initially, when stopped for some time the effect gets weaker but is still there.
Something in the transmission builds up so much creep that, after stopping the car, when shifting into P the engine jumps up about 200rpm when it's freed of the load and then returns to its normal idle when the transmission is no longer putting up resistance.

Has anyone had a similar experience in a 4.2 N/A X350? I do suspect the torque converter, maybe the lock-up clutch, but looking at what the TC will cost to change I'll rather collect some feedback first. What would the transmission gurus here suspect to be more likely? TC or transmission itself?

Maybe a small air leak? It's like having your foot on the accel pedal.
Or a mis-reading MAF? Not so likely, I think.

Look at fuel trims & MAF readings.

Fuel trims are fine, fluctuating around 3.6% LT and around 0% ST, all four in a reasonable range.
The MAF readings also look plausible in OBD. "Real" idle in P has around 4.2 grams and when it has to fight the transmission in D this goes up to around 6.6 grams

And a leak probably wouldn't let the engine jump when switching from D to P.

A leak would (often) have given a high idle.

But a leak can also occur due to a (vacuum) hose flexing as the trans / engine / brakes fight each other.

Just ideas.