I had a problem with my 4 cycle 70
HP boat engine with Fuel injected engine. It was running fine when winter set in and it set for 3 month. Next time I used it, it started fine, idled perfect and would power up fine, then after running a few hundred yard, it would stall down like it was starving for fuel, then it would suddenly power up to full throttle and run for a while then the
RPM would drop back to about 1800 at full throttle. I checked the plugs and they looked fine, the spark was blue hot (didnt have a voltage checker). I even replaced the fuel hose and tank and nothing. I was ready to take it to the boat shop and stopped in to schedule an appointment. The service tech said change the plugs. I told him they looked perfect, whereby he said those cheap (not so cheap in $$) Japanese plugs that Evinrude puts in break down. So I spend $24 on 4 new plugs, problem solved. The engine had less than 50 hours on it when this happened but it was 3 years old.