have your injectors popped... I had a set of stock 215's that would blue haze like no other. I popped them, and fuel was dribbling out of almost every one of them!
also, as stated above, check your timing. I had 370's in a mis-timed truck (12.5*!) and it would blue haze like mad also
*edit* I just read about sputtering and popping when it's cold out... DEFINATELY check your timing!!!
