I have the same problem with the sputtering. Mine sputters only after like 10 15 minutes after warming up I guess enough time to heat the coil up. I tried everything from new filter, rejetting, and different octane level. Nothing would work. I have a temp gauge so I know its not over heating. I just ordered the Ricky coil so I will have it tomorrow but wont be able to test it for a few days least till the rain passes so I will let you know if that fixes it.