Hello everyone. I have a 1998 Caravelle 188 with a 4.3 mercruiser. The boat was running fine then all of a sudden it has lost power. It takes forever to plain out, has a slight vibration under acceleration, and has lost about 7mph top end and won't turn over 4k rpms. I have checked the choke plate, and replaced the plugs, and checked the distributor cap and rotor which looks fine. I'm lost and don't know where to start next. The wierd thing is it did this about a month ago and did it for about an hour, then ran fine again. Ran fine the next few outings and then started again 2 outings ago and hasn't stopped. Anybody run into this problem?