I have a 1999 Yamaha F9.9 hp Kicker motor , I also have a 703 remote throttle control with electric start. I am having trouble holding my trolling speed . The motor runs fine for a few minutes and then it starts to bleed off or lose rpm's to the point of dieing. I've noticed that there is no vent on the fuel tank and I'm always having to open the gas cap to release the vacuum , I'm thinking that the vacuum might be the problem. Hoping to find a little help.