M5 e39 doin my box in

If no codes are set, i would suspect an intake or exhaust restriction- clogged air filter, catalytic converter, smashed exhaust pipe, or possibly a failing fuel pump is causing you to loose fuel pressure. Check your short and long term fuel trims. If they go more than -5%- i would suspect a restriction; if they are more than 5% positive- i would suspect lack of fuel.

It would probably be a good idea but if that doesnt work try plugging in an error decoded and see if it comes up with anything

I would say the torque converter came out of the trans pump
Shake or move the converter until it seats
While your in that situation, did you put at least one quart
of fluid in the converter? Good idea while you can still drop
trans some & pull the converter.
I have seen trans burn up on the lift, after a rebuild, for many reasons ,some you don't need to know about.

I have had this before it is best to change the cam and crank sensors as a pair. as a week sensor will affect the other sensor.and give a false code. as these work together. it is best to change both at the same time. i changed the crank on mine after the cam and it sorted it out. crank sensor is located near to the thermostat and under the exhaust manifold. make sure you tuck the wire away from the exhaust manifold . other end of the wire is fitted to the under neath of the injector cover and is cliped in place very easy to replace

15w40

You have a ground connection intermittency issue. Check the blinkers socket clean rust and retghten

This sounds like the mass air flow sensor has gone bad. Do you have a check engine light on? This sensor is in line with the throttle body and the air filter box. Common symptom.

cam shaft position sensor at front of engine on top, i ve done a few of them you need to replace it.

check the fuel filter and the EGR valve