BMW Repair: E46 M3 EML light and erratic power, fuel pressure regulator, lambda sensors

Question

Fault report I have a 2001 E46 M3, EH76140.  It's done about 45k miles and has a problem that's developed over the last 5k miles in spite of attempts to rectify by BMW dealer.  It starts and idles fine, but through the rev range the power is rather erratic.  It began with no symptoms other than the EML light coming on while cruising on French autoroute.  The car ran fine and made the trip without a hiccup.  Since this, the acceleration has gradually become a little jumpy, and sometimes under heavier load the engine switches to a "limp-home" mode that the engine fault report refers to as "Cat. protection function".  I don't feel generally that the car produces the power it should either, and in normal driving it's now jumpy, particularly when cold.
I've taken it to a main dealer who first blamed lack of fuel in the tank, then found a split seal in the inlet manifold, but the problem remained and they then replaced the fuel filter, also to no lasting effect.  I wonder about lambda sensors and about ignition timing, but there's nothing in the fault reports printed out by the dealer that indicates either might be the problem.  If anything is a recurrent problem it's that I'm out of fuel!  I have a .TIF file of the Diagnosis Report printed by the garage if this might help.  Please ask me questions if you need to know more.  Any help gratefully appreciated.
Justin of Chesham, England.

NOTE:  ATTACHED FILE MUST BE RENAMED TO "REPORT.TIF"

Answer
My first thought would be to check the ignition system.I know the mileage is low as plugs should be replaced at 100k.I would remove them and check to see how they are burning,while there I would inspect the coils and boots for arcing.Although it is OBDII it may not be enough to set the light.You mentioned the"cat protection function" that is why I would look at this.I was unable to view your file.The fuel pressure should also be checked,just replacing the filter isn't a true fix there may be a fuel pressure regulator that is bad.