I have a 1988 carver santego 2767 with the mercruiser 3.7lx motor. Late in the season I traveled a long distance to meet up with friends approximately hour and a half trip and was there for a couple hours and headed back. When I was coming out of the bay to lake my port engine started misfiring so I throttled back. After several attempts to try and smooth it out it quit. So I got back to my dock about 3 and a half hours later on one engine. I changed the plugs and wires and it started up and after it warmed up and I headed out it started doing the same thing. I was told by the local marine part supplier that I needed to change out the distributor cap and rotor. He said I'll probably have to do this every other season or sooner. Does this sound reasonable. I'm going to change it out in the spring to see if it works. Any thoughts?