Bobby The fact that the cylinder starts to fire if you hold the choke on means that you are probably not getting enough fuel from that carb. Since the problem clears up after 5000 rpm the lean condition is probably in the idle and low speed system of that carb. the fuel is supplied at this system through the two small holes in the bottom of the bore of the carb. One is directly under the forward lip of the slide and the other is the hole drilled on an angle closer toward the motor.the fuel is supplied through the pilot jet from the float bowl. the air for this system comes through an air passage from the front of the carb, the upper of the three holes you see. the amount of air is adjusted by the air screw on the side of the carb. Make sure this screw is the same amount of turns out as the other carbs, usually one turn will do. next make sure the pilot jet and the two small fuel passages are not plugged or restricted in any way. after this the only other thing that comes to mind is to check your slides to be sure that that carbs slide is not lagging behind. When the cables a adjusted correctly all slides lift at exactly the same time. good luck hope this helps.