recently my blazer came upon a rough idling while in drive. if its in park it idlles perfect. then made a full tune up to what my cause bad idling but thats not working. so i got ob tested and it says the exact things i changed. so much for a machine that do no good. so can anyone tell me what they think is wrong im done with paying for something thats not the problem.
thanks.

 

What kind of plugs did you install? Hopefully the correct AC Delco's and NOT something like Bosch platinums etc... what was the gap?
Did you change the fuel filter as part of the complete tune up?
Have you considered a vacuum leak?