Take a look at my first posting '1995 540i Fouled Plug' dated 8-5-2010.
I've changed all (8) plugs and the #8 (the fouled plug) cylinder ignition coil and still have the 'no-fire on #8' problem. My next step is to put an ohm meter on the wire from the DME to the #8 ignition coil. After that, I'll try to get the DME checked. I'm now about 100% certain the problem is an electrical one - compression is good, leakdown is good, the problem is on the 5-6-7-8 cylinder head as the drivers side O2 sensor is 'faulting'. Have also replaced this O2 sensor. #8 is not firing.