If the FI warning light behaves normally and there is no error shown, I�d guess you�d want to be looking at the things that don�t show a code, but can cause poor/rich running/bad fuel economy:

• Ignition HT side fault (only the primary LT side shows an error), but the HT side can be tested in diagnostic mode D30.
• TPS bad/dead spots? Only shows an error if shorted or stuck, not if it�s erratic, got flat spots or giving duff readings. Although it can be tested in diagnostic mode, it only tests for short circuit or if it�s stuck. You�ll need to check that the resistance (max) reading is within spec and also that the resistance changes smoothly from closed to open. Max should be 4.0-6.0Kohm and the range 0.0-6.0Kohm.
• Fuel pressure out of spec? Too high? Too low? Should be 3.31bar at idle. Fuel pump OK?
• Injector blocked, dirty, leaky? No error code as such for faulty injector, but can be tested in D36. Check resistance is 20ohm? Run some injector cleaner through?
• Fast idle/cold start mechanism faulty, sticky plunger, stuck on, leaky vacuum? I have heard of a few of the bodies crack and cause funny running issues.

Clutching at straws really, but there might be something in the above list to make a start on?

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