Sluggish is most likely a scaling issue. Dirty pots usually gives you spiking.
Go to the controllers section in the game. Click on the fighter stick in the drop down menu, then click the advanced button. Select each axis and watch the input line in the blue box, as well as the input numbers where you clicked for the axis. If the numbers are jumping all over the place it is most likely dirty pots. Dead band slider can get rid of some of it but you really don't want to more it up off the bottom much.