vermsta is right, most of the emission system only takes effect when the car is fully warm, thats why they warm it up well when you smog it. here is a suggestion, I may be wrong but it is just something to think about, people on the S2K forums I think its S2K.com or something, were saying that a lumpy idle and the car dying etc when it is cold could mean that the valves need to be adjusted. They also said it has the lumpy idle or dies when the valves are too tight and if they are too loose they will "valve tap" It could have nothing to do with your car but it is just something to consider....... did you check out your IACV abd fast idle thermo valve? thing is, when those get dirty they tend to stay open and keep the idle too high instead of too low, does your car run OK when it is warmed up?