I purchased a left over 2004 8hp high thrust to use as a trolling motor this year. Sometimes when it starts it's great. Other times it starts, runs for about 5 seconds bogs down and floods. Other times I have to start it 3 or four times to keep it running. Sounds like the auto choke to me. Do you think I'm right? I've had it in for service once with no luck. The unit is electric start with power trim and there is no manual choke on the controls. 