I'm no expert but:
in order:
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18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
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check the battery terminals to make sure they are tight.
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17951 - Angle Sensor 1 for Throttle Actuator (G187): Signal too Small
P1543 - 35-10 - - - Intermittent
17580 - Angle Sensor 2 for Throttle Actuator (G188) Signal too Low
P1172 - 35-10 - - - Intermittent
17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 35-10 - - - Intermittent
17987 - Throttle Actuator (J338): Adaptation Not Started
P1579 - 35-10 - - - Intermittent
[/ QUOTE ] looks like a throttle body type issue - do you know someone with a similar S3/TT you can swap it with?
If you can do a throttle adaptation via vag-com (basic settings, 060), then see if the performance returns. If it does return, but drops off again after a period, this could indicate a dodgy throttle body motor unit.
Also check out the vacuum hoses connecting the N249 valve with the DV etc.
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17536 - Fuel Trim: Bank 1 (Mult): System too Lean
P1128 - 35-10 - - - Intermittent
16486 - Mass Air Flow Sensor (G70): Signal too Low
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seen this before - most probably caused by a faulty air mass meter. if you clear the codes, then try unplugging the electrical connector off the air mass meter and see if the performance improves. If so then your air mass meter is shot and you can get an exchange one cheap enough from Audi.