Timmah is right and i would of said the same but I was %95 sure it was to do with the engine not been upto heat, my cen used to do it when i had the 2 stroke in it the first start of the day you would need to tak it easy. once it was upto temp it would run great for the rest of the day... even if you stopped using it for a hour or so then went back it would still run great, just the first start of the day (who likes been woken up in the morining and asked to do hard work right away) ... My t-maxx is the same.