Bmw E34 525i 12v 1990

[redworminator]

my bmw wont start on the key it just turns over but doesnt fire, some times it will start with plenty of gas but not often.i have replaced the plugs, filter , oil, crankshaft position sensor, airflow meter, idle valve, checked the coil, leads and the fuel pump and relay but none of this helped, i then booked it into a bmw dealer and they told me it was the dme unit so i got a replacement one and this didnt work either.
as you can imagine this is very frustrating as the car always starts when i bump start it and it runs faultlessly so has anyone had the same problem if so i would be grateful to hear any advice, it has to be something that is only used in starting the car but i am not a mechanic so i am stuck

[sp0rky]

That really does sound like the DME to me... how odd.
When it turns over, does it sound any different than normal??? Like its stressing out?