hesation when holding constant rev

Colliemcc

Petty Officer 2nd Class
Joined
Jun 28, 2009
Messages
143
04 Volvo Penta 4.3 GL-D

Today was the first day that I ran my boat for more than a few seconds this year.
I have not had it running in 10 months had it running today at idle for about 10-15 mins until up to temp. revs up ok when I give it short bursts of revs, but when I move it up slowly it kinda struggles till I open the trottle up a good bit, but when I raise up the revs slowly again it splutters.This happens when I hold it at a constant rpm
Is this just because the engine has not been running in over 10 months a need a little run in time again.
I have just replaced the riser gaskets on each side.
 
Top