i hate t-pain... what a joke.
but anyway, ill test some settings.
try and lower the "attack time" to 1 ms
-- also, you may want to choose chromatic scale, and then use the pitches that are in the song you are doing.
alternatively, you could use reavoice and control it via midi?
t-pain sucks and that sound should die immediately.
i dont even know why im helping.
btw, welcome to the forum