I have a 2003 4.3 mercruiser with throttle body. I have encountered a problem where if the motor has to be started on the first attempt at turning over by quickly placing in neutral and increasing the throttle. If I fail to start it this way the engine will not start and floods out. Once started I have no further problems starting it for the rest of the day we're on the lake. Turn the key and it starts right up. The motor runs fine once it's started in this fashion. Any ideas or recommdations would greatly be appreciated.