Hello everyone. I bought a boat last week that is in very good condition. It hasn't been run in four years and before it was put into storage it was professionally winterized and stored indoors. I mixed some new gas in it as well as new spark plugs and started it up, it ran perfectly for about 30 seconds and then the plugs got fouled and it started to run rough and backfire. Also, It will run fine when the idle rpm is up but as soon as it is brought to neutral before engaging the forward gear it sputters and dies out...any ideas what could be wrong?