Ok 4x4, with 5.9 long tube headers. Starts up ,idles fine as long as in Park or neutral. Once you place it in drive it idles erratic from 500-1k up and down. And you can smell gas at redlights.Fuel comsumption is way up.When you press the gas it feels like it has a 10k trailer hooked to it. Very sluggish to gain speed. It goes thru all the gears,and thru all has that towing feeling. Takes a lot longer to get to 55 than normal. Once at highway speed 55 every once in a while it will shudder.Almost like a dead skip. The motor revs perfect.No skip. Had the tranny checked out by 2 different shops because I thought maybe it was there.But both shops say tranny is fine.On down hill it will coast fine,even picks up speeds,all wheels travel freely when off ground. The only code is for an exhaust leak right near the o2 sensor already knew about.