The choke should be closed when the unit is off via return spring. Make sure the spring is in one of the three notches, and that the other end is hooked around the choke properly. Make sure there is no drag or sticking of the choke movement. The solenoid, when energized, opens the choke and will hold it open while it is running. The choke should be flat and parallel to the venturi surface, and not in contact with the plastic. Do not bend a choke plate for any reason other than to straighten it, which is sometimes best done after removing it. Backfires can bend a choke plate upward.
When you press manual, the controller runs a choke pattern opening and closing the choke, but once started the choke fully opens and remains open.
Your unit should not run better at full speed with the choke closed rather than open as it should be. That sounds like the generator needs a complete going over.
Check your throttle shaft and butterflies. The tack-weld on the near end of the throttle shaft should not be loose or broken. Push the stepper arm to the left to place the unit in full throttle position. Then, if your pinkie finger is small enough, stick your pinkie in each venturi and feel the edge of the wide open butterfly. It should be wide open (edge of butterfly should point straight to the left), both butterflies should be in the same position, and no excessive movement or wiggle. Touch them gently, they can cut your fingertip. If a butterfly seems loose, is partially closed, missing, then we can cross that bridge when we get to it. If your pinkie is too big find someone with a smaller hand.
State your problem, not your diagnosis.