Ben,

The symptoms you describe resemble a problem I recently had damn near to a
"T".  In my case the bus had just come out of a 5-year storage and the gas
tank was rusted to hell and gone.  Rust is probably not your problem, as
it sounds like a daily driver, but a clogged gas filter might very well be
doing you in.  One of the beefs tha I have with FI is that so many
different problems may cause the same symptoms, but it sounds to me much
like you are not getting enough gas, either because pressure in the fuel
ring is low, or because the FI system is not injecting enough into the
cylinders.

If you have the bucks, take it to a shop to have the pressure
in the fuel ring measured.  If it is ~30 PSI, then there is an FI problem
somewhere.  If it is much more or less than 30 PSI, then the problem is
blockage in the fuel ring, bad gas pump, or bad pressure regulator.

If you don't have the bucks, I would advise changing fuel filters as a
cheap easy first step (let a little run out of the tank to check for
blockage there as you do).  If that doesn't help and you have a bunch of
spare FI parts, try swapping out the flap valve.

                           H Steven Dolan
                           Alexandria, VA