I had a new high pressure fuel pump put on my engine at 200hrs. The boat ran fine the rest of the season then was put away this past winter, this spring the engine continued to have issues. At first we thought it was the pump again but that turned out to be fine. At this point the engine runs till it hits 3800 rpm's then surges like it wants to go but will not. Engine normally runs to 5400 rpm's. I have had the dealership take a look at it and they can not figure out the problem. They have tested the plugs, throttle control sensors, fuel pumps and fuel control valves and everything checks out fine. Any ideas on what the problem may be. ie: I have twins and the other engine runs great.