i got a 2006 t660 turbo st with 2500mi on it. It runs rough intermittently and seems to get worse as it warms up to the point where it will not stay running. I thought it was only hitting on one cylinder and when i pulled the plugs that cylinder had the best spark. That plug had the best looking spark no matter which coil it was in so i replaced all three plugs and there is no change. Anybody see anything like this out there? No "check engine" light is on. Any info. helps thanks!

Sounds like a sensor. You might talk to the dealer who originally sold the machine, or the one who sold it to you if you got it that way. Any good service department should be able to ask the questions necessary to focus the problem most likely.