Here's a thought, I'm doing an upgraded 340 lpfp in my e60, this is difficult from the e90, but what I found is the filter. When I pulled my filter, clear fuel had come out when I pulled it out of the tank, when I brought it to the bench, and blew in, a lot of black crap came out. So I ordered a new one, Bosch fuel filter for $80, well worth it. I found this to be original with the fuel filter, I've never had a fuel issue, power, or mis, I'm doing the upgrade for my motor swap, but found out that, these should be definitely changed at least every 30k. I never thought this would be a lifetime filter.
