Help?..I have a 2001 5.0 mercruiser, 180 hours. I bought the boat this season and issues since day 1. Things I have done is changed cap, could not get rotor off, didn't want to break it. Starter and fuel sender. Now I have an issue I discovered last night. When above 3000 rpms the engine fluctuates a few hundred rpms up and down, when decreased below 3000 it runs fine. Any ideas?