Car wont start

Have you repaired or replaced your DISA valve? It is the throttle body box attached to the intake manifold. You cold also have a dirty MAF sensor. I just went through a similar situation with my E39 2.5.

Most shops will also recommend a smoke test to see if there is a vacuum leak. You could have simple rubber vacuum hoses going bad. The last possible option is you CV valve or oil separator. The vacuum line dry out and need to be replaced if they have not already been replaced.

Check codes agian as Tom said you should have something in there for this. As Michael mentioned you should check for vacuum leaks by spraying throttle cleaner around the intake and intake boots and see if engine revs up. Also you should check your crankcase pressure by removing the oil cap while the engine is running. It should take a slight amount of force to remove. If it excessive then you need to replace your oil seperator that has failed causing the engine to suck unmetered air and running lean. Also you could unplug the mass airflow sensor and see if it runs better. Just a few suggestions please let us know how it goes.

My E53 had a similar problem (and a new one which is why I'm searching). The car would run and drive but very herky jerky and felt ready to die the whole time. Turned out it was my fuel pump dying. Replaced it under the back passenger seat and ran perfect again