The only mod is a cobb intake. It only does it when the car is warmed up . Weather this morning was dry and about 40dgs. I live south about 35 miles from Salt Lake. One other symptom I forgot to mention is a hellacious whistle similar to a window whistling going down the road that somewhat tracks rpm. It sounds like its coming from under the hood. Once it "resets" the whistle stops. No engine codes are thrown either.