Ran the 489 with 4 hrs on it past 4000 rpm today...could only get it to about 4500 rpm and 43 mph on the GPS...anyway, noticed the oil pressure was only about 20-30 psi as i throttled it back to around 3k rpm, temp approaching 180,noticed a slight miss, then engine died. Opened engine hatch, water boiling in the hoses, got a tow back 1/2 mi to marina, checked raw water impeller, it was fine (replaced it with a new one anyway since I keep a spare on hand). Fired boat back up, noticed that water circ pump wobbles pretty good. I'm guessing either water circ pump or stuck thermostat?? Boat has not overheated previous outings, however today is the first time really have gotten on it.