I have a 454 mercruiser magnum. Just boat the boat (24 foot baja 240 sport) and was out just my second time. Cruising at WOT at about 55 mph and then the MPH dropped to about 25 mph and felt like the boat was struggle. I let off the gas brought it down to idle and then it died. After about a ½ hour I get her started again. Put it in gear and stalls, do it again, again, again. Finally get it to stay in gear and go. If I would give it gas the motor would rev up but the boat would only go up to like 10 mph. The motor is making a clicking noise, that gets faster as I give it gas. I think I toasted the plugs. I reached down to feel a plug, while the motor was running and I was shocked so I am thinking the wires are toasted too. The only other thing I have done to the boat that may have caused this but I do not see how is put a system in the boat, 2 10 in woofers with a 500w amp and Four 6 in speakers with a 1200 w amp., radio and satellite radio.<br /><br />Here is the best part. So I limp the boat home at 5 mph, takes about 2 hours to get home through memorial weekend boat traffic (sucks going through channels at 5 mph when everyone is doing 50 !!!). I have it a little over idle the entire way home, get to my canal, which is not too wide, so I have to drop it down to idle. It dies, start it up give it some gas, let off the gas, stalls, repeat this five or six times, now I am ¼ way down my canal. Does it again and then the starter breaks, just keeps spinning. So I am dead in the water. There was a small breeze blowing down my canal (my house is the last one on the canal) so I put up the engine hatch and the wind pushes us slowly down the canal to my house, was the best docking job I have done yet!!!.<br /><br />So I know I need a new starter, regardless of if I need plugs/wires I am going to change them, along with the carburetor filter. What else could have cause this and what should I check?<br />Thanks