I have an 09 Street Glide, 96" motor, high flow, V&H 2into1 and 204 cams. Tried to tune it with the TTS Mastertune. The power and torque are fine at 100% throttle and pulls good under load, but if I roll on the throttle at low RPM's, under 2000, the bike sputters and backfires then takes off. I can't find a tune for this engine combination. Any ideas what would cause this condition?