I have a 2000 A4 1.8L turbo, that runs really rough when first started the smooths out to perfect idle after a minute. But when I place it in gear to drive off it hesitates and registers codes 300, 301, 302, 303, 304 all of which represent cylinder misfire. Will also throw 1138 to rich at idle and 1129 long term lean. I have changed the air, fuel filter, fuel pressure regulator and suction jet near the intake. Mitchell on demand ervice program suggest pressure side air leak between turbo and intake. I have inspected/ replaced many of the vacuum lines and preasure ducts. I just drove it 1K miles in 24 hours at highway speeds by pulsing the accelator to keep it going.
If I hold the accelerator in a single position the engine sputters and begins to car slows. I am thinking it may be the throttle assembly, ouch $600 guess. Any thoughts???