i have an 04 roadking that started to miss bad at steady speeds . its fine if accelerating but as soon as i leavles off it misses and backfires. had it at the dealer today and he said intake leak . but a hundred dollers later and new seals it still does the same thing. i put new plugs in and helped for a short time but never was great. also noticed rear plug had black carbon or something on it after only 35 miles. they also hooked it up to a tester and it showed no codes and fuel pressure was right on . any ideas where to start now ? dont want to pay 100 bucks an hour when they have no idea whats wrong. should also add i have stage 1 with a tfi tuner . i took it off after trying everything else but still the same.