Have a 5.0 Volvo penta gxi-b 2002 model. Boat only been in water 3 times in last 3 years. It was on empty when I got it. I filled it up with gas and put 2 cans sea foam in it. Took it out and it will crank up and idle just fine. When I gas on it and get up to around 30 mph it shuts down and loses power. It starts popping real bad. Let it idle for 3 or 4 minutes and it will run fine up to 30 mph again and start doing the same thing. What would my first step be?