I have a 1990 560 sel, I have replaced the fuel distributor, EHA, fuel pumps, etc, and also done a complete valve job and replaced the timing chain, but the fuel pressure was a bit high, approx. 95 psi. The car runs great for a tank or two, but as the mileage begins to plummet (sometimes within a few miles), the car loses power, burns really rich, and dies. It seems as though the fuel pressure is too high, and also not constant.