Engine problems - Any ideals

Hi,

I finally set up a mooring and got my boat and engine (Alaska 500 & 60 hp 2 stroke Tohatsu) in the water after sitting outside my house for 18 months. This is the first time I used this package, bar on collection. Im having a few engine issues and I'm wondering if anyone has has similar issues with an easy solution before I take the boat out of the water in a few weeks. Before winterising I will have a mechanic look into the issues. prior to getting her wet I replaced the plugs & oil the mechanic cleaned the carb jets and confirmed she was firing on all cylinders.

Symptoms. The first trip was a 3 hours trip to get to the mooring. It ran rough beyond 4000 revs an occasionally jumped into high revs. I Turned it off and fished a couple of hours and it ran smooth & fast for the 15 mins to shore. The second trip it wouldn't run beyond 3500 revs and but would occasionally burst up to 5/6000 revs on its own. It would tick over at idle for about 5/10 mins but would eventually die unless i gave it a bit of idle throttle.

Im thinking the float chambers need a good clean out, any ideas ?

Aye, sounds like blockage from description....
Have a peek into the tank and check the fuel filters too.

Thanks Jim.