Yup bad wires will make it run funny. I just had a set of MSD 8.5s go bad on me. They were only 8 months old so I was positive it wasnt them. I took it to Ford after changing plugs didnt do anything for a diagnostic. They told me it had an intermittent miss on one cylinder (duh). They also said it was # 2. I tried an old stock plug wire and it fixxed it up. I have Motorsports wires ordered from Steve at Houston Performance.