depending on the angle of the slope, the engine might be starving for oil - the Range Rovers have a special thing that they used to add to BMW engines to allow engine operation at 45 degree slopes... i don't remember what it was and have no idea if the oil starvation may present itself with your symptoms but - something to consider...

it did it again today, the angle was less than 45 and it was in rear. i let it warm up a bit before moving. the engine shuddered on a flat surface off my drive way and the engine light lit up, and it shut off. this happens in 3-5 seconds i did not have time to put it park positron.

Just checked my idle rpms, those seem to be working at proper rates.
most likely going to replace fuel filter next.
no codes appearing.

do the I-6 engines have that chain guide problems that the V-8s have?

http://realoem.com/bmw/diagrams/c/s/6.png

From this diagram, it looks like it does. I don't know, I never heard of a guide failure on the M52's

i dont know, its just the car doesnt sound so healthy at the moment. It hasnt stalled again.

So i will perform a full stage 0 on it. the plugs, fluids etc. its at 93k. preventive maintenance is key!