I have a 1981 Kawasaki KZ550. This recently started happening: I will be riding, then pull the clutch in to shift gears, and as soon as I pull the clutch in the engine stalls. This has happened every day that I have ridden it recently. So, when pulling over and trying to start the bike again, it will only start it I close the choke completely, twist the throttle, start the motorcycle, then keep the rpms up very high. If I let the rpms drop below 4k it will stall again. This is unpredictable, and it seems to happen randomly. Sometimes after I start it up, it will go back to "normal", but most times it doesn't, so I keep shutting it off then trying again. I have no idea what this could be. I thought that maybe it was a bad coil and it was running on half the cylinders, but I replaced both ignition coils and have noticed no difference. Any help is appreciated.