I agree with 8man check your needles if they are very easy to turn you may have a problem there. but after the heat cylce bit lean the hsn maybe 1/8 of a turn and the same to the lsn to drive it around also check your temps you want the motor to be able to reach close to 200 now but dont go over 230.
drive it around at those temps for a tank or two then check your breakin by removing the plug and rolling the motor over by hand you shouldnt feel the piston grab at the top if it does you need to do a couple more tanks.
do that till you cant feel the piston resist at the top or feel just a tiny bit of resistance. then you can tune it for performance. have some patience.
all my sts motors have held there tune very well and can run all day long without messing with the needles