lean while cruising you should be in the Main circuit of the primary side of the carb. jet up 2 sizes and see if it helps and maybe you have a miss in the ignition.
check wires etc.
Pls don't tell me you got TAYLOR crap wires on the motor and if you got an MSD distributor check the cap and rotor for corrosion or tracking.
Cruising stumble or sputter can very easily be caused from too large IAB's as well, ran into that myself. Wanted to sputter when I first got my carb, played with and checked everything, swapped carbs and ran fine. Lowered my IABs about 5 sizes, reset mixture screws and wala.