Sounds to me like you got a motor that is just broken in. Hopefully that is the case. How does the pinch feel without the plug. Does it seed at TDC nicely. Also with the plug how is the compression. If these 2 things are good than I would run the motor rich for about the first 7 tanks just to make sure of the break in and then go for the race tune. Make sure it is shimmed for the fuel %you are going to use.

hope this helps,

DJ Apolaro