Thanks, I think the filter must have had an internal slow leak letting fuel get into the vacuum line (pressure regulating valve?). I wish I could figure out better if that line is just to vent it or actually hooks to a vacuum. Either way, I think the fuel must have been coming through the fuel filter rather than back down the line from the other side.

I'm hoping this is the cause of the X5 occasionally idling really low at start up (infrequent, but will idle/stutter around 2-300 for a minute occasionally). It hasn't done it since I replaced the filter, at least.

Thanks again!