[Simon Jordan]

I have owned the engine since new and know it does not like to idle for too long. However the problem is now terrible, the engine will cut out as soon as the revs come down. It will more often than not cut out as soon as you engage gear. It will not start easily. Then is slow to pick up using the manual throttle. It only runs well on half to full throttle. It sounds like it is fuel starved at low revs, but I have replaced the fuel line, plugs. One thermostat is on order as it is stuck open.

[Dhadley]

Welcome!Go ahead and change both t-stats. It sounds like the carbs may need a good bath. Those motors should idle great no matter how long.Make sure youre using fresh 87 octane and Champion plugs.That motor has the Quick Start feature. If one t-stat is stuck open and it happens to be on the bank that has the sender for Quick Start, then the motor could be stick in Quick Start. If so, and youre trying to get the motor to idle down manually it could act as you describe. If it ever does come out of Quick Start it will be set so low it will stall. The idle has to be set with the boat in the water (for backpressure) and the motor out of Quick Start.Make sure the water control valve (controlled by the throttle arm) is working properly. In fact if youre going to change the t-stat, I would go to the 1993 style t-stat. Youll need the cap and spring for each head but you can eliminate that control valve and those hoses.Good luck!