I have a 1989 740 non turbo which is hard to start when it does it stumbles then runs and idles fine I can idle or drive the car for about 10 mins. and it will stall. It will start again but it has a hard time, I checked fuel pressure it fine about 40 to 43 psi running, tach reads fine it fals when it stalls and I changed the rpm sensor. I did notice the radio supression relay gets hot so I opened it and held the contacts together and it still stalled so I replaced it and got the same results, as for the pump relay I changed it as well and no difference 10mins and it stalls. If I hold the throttle at 1000 rpms or above it will not stall but does studder once or twice under 1000 rpms and then of course back to idle it will stumble and stall and some times even diesel before it stalls. I have even changed the power stage too, no difference all with parts from a good running car. Could it be the engine control unit?? No. 1 fuse does not get hot nor does the pump relay. And when it stalls there is still power at the coil which I have also changed. Help:-(