Just could call him and he sent me emails:

Well I think I finally found the problem. One more 5:00 am morning checking things before work!!

After checking and swapping MAF's, DME's, DME relays, I made a breakthrough discovery, My car was in a sort of Limp Mode. I crawlled under the car to check the CATS and noticed that the one side was cold to touch. Thinking spark or fuel issues I checked the fuel pump relays, coil, induction test on the plugs, vacuum lines, fuses - all checked ok. After recieving an idea from Shogun and Harywithit I was heading to Johan's site for the fuel pressure regulator change. Part way through it details jumping the fuel pump relays to check for fuel quantities. Sure enough, the side that wasn't working wasn't receiving any gas!

All I can think of is in the morning I'll check the connector at the tank to ensure everything is good to that point, before coughing up $200 or so for a new fuel pump.

Having said all this and seeing the light at the end of the tunnel, does anyone have any other ideas in case this doesn't pan out?

Real
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That is the status as of now.
If any ideas/proposals, just me me know.
I am checking now for a used pump in Japan. Or does anybody know what other maker than Bosch can be used. BMW p/n for the pump only is 16141179710.
Bosch p/n (not sure) is E300-150664
Regular price is $ 306,-, so it will cost here in Japan abt. double that price.
Checked various online vendors in USA like expressautoparts.com, autopartswarehouse.com, prices 237,22 and 215,47.
But there is a pump at bavauto.com with their p/n GFP316 which costs $ 199,95.
That seems to be not a Bosch pump. Does anybody know the maker of another brand for this pump and/or the specification/size etc. for the pump? Maybe they are also available in other japanese cars, so then we could get a pump much quicker and probably cheaper herre in Japan.
Thanks