On my pk100 motor while idling after it's warmed up the rpm seems to go down very slowly until it stalls out, once I restart the motor the rpm is back to normal then repeats again, what kind of symptom is this? I am running a bit rich (I can tell from rpms dropping a tiny bit below idle after I rev and climbing back up to idle) for safety of the motor initially when testing. It doesn't seem like a major issue as the rpms are back to normal idling after revving.