A3 1.8T Quattro idling and power problems

Can anyone help me as the dealers dont seem to be that useful. I've now had my car in twice to the dealers complaining of idling problems when the engine is cold (especially) and then power reduction which
result in loss of power and then a surge. Initially the lambda sensor was reset but not replaced and then a week later the engine management systems warning light came on. I've now had the air recirculation and dump value both replaced and within a week the same problem although no warning light, yet. This morning the engine stalled twice after chugging for a good 4 or 5 mins. When the oil temperature is normal it seems ok but I'm stumped and dont want audi fobbing me off, again.
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Could be the Coil Packs When my A6 1.8T '01 coils packed in the engine went all lumpy then lost nearly all power but would come back on again for a bit. Lucky enough had both packs replaced under warranty.

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