If it were the pick up coil, the problem would be common on two cylinders, most likely, as one of 'em works 1&4, the other 2&3. If the problem gets worse with more throttle, needles? main? Simply over carbureted? Could be the float needle is stuck part way? Floods on low fuel draw, starves on heavier use?
I'm not a carbbie magician, so mostly this are guesses that could be.
Good Luck. I'll yield the floor to a real magician.