I second the smoke = dead turbo seals. It happened on my brother's car. I think the smoke is more noticable at idle because of the low volume of air coming from the tailpipe.

Also, make sure that you hooked up power to the O2 sensor. The brown wire in the "battery area" needs switched power. That would cause the O2 to read wrong and mess up your A/F. I mention that because the Heavy throttle wiring guide kind of skims over that conenction.