1995 BMW 840 iNJECTOR

Electrical problem
1995 BMW 840 V8 Two Wheel Drive Automatic

Hello,
We have a problem with a bmw 840 v8 94/95 year,
With Bosch Motronic 3.1 0r 3.2. The car engine started to run rough and the scanner showed, that a AFM & Crank sensor, these where replaced and the engine still runs rough, when checking the engine it seems like it is not running on all cylinders especially number 8, changed the injector and coil for that cylinder, no change, checked the wiring for the injectors live circuit is linked together, and it appears that the ECU is earthing the injectors at the correct time in the firing order sequential, Number 8 cylinder if you put a bulb into the connector, and the ignition ON, The bulbs stay lit, the other cylinders work as they should OFF untill you crank the engine seems like the ECU or somewhere else is earthing the number 8 cyl, I traced all the cylinders injector plug connectors back to the ECU Plug, continuity, I notice on a wiring diagram that the live circuit for the injectors come from the main relay pin 87 after the ecu has been powered up, the iscv and air flow meter are on the same circuit as the injector live also the 02 sensor relay, the owner has had the ecu checked twice but it seems like the problem is the ecu, any help would be welcome
Regards Dave