Today my '89 Blazer(350) went nuts... The idle is horrible or I think I can say there isn't any idle. Without pushing the gas pedal the car dies, keeping the RPM's over 1500 everything is fine but under that, coughing, missing etc etc. I cannot find anything, the only code is 12(everything should be ok?!)... The only symptom is that I think is that it's runnign too rich, because after a little "RPM-session" there's smoke coming behind the injectors. Any ideas would be real helpfull!!! Thanks.