Rough running vindicator 200

I have a 1995 Evinrude Vindicator 200 HP. The motor starts fine but once it gets warmed up it won't stay running when it's in idle. The motor also shakes alot when idling in and out of gear. The prop looks good so I know it's not out of balance. It almost seems like it's mis-firing a plug. Does this sound right? I'm also thinking I may have a dirty fuel filter as I've never changed it since I've owned the boat (3 yrs)
Any suggestions? I'm gonna call my local dealer tomorrow and get pricing on plugs and a filter.

Thanks in advance http://xs-s.com/zf/images/smile/embeer.gif

Have you done anything to the motor???

The only thing I've done was take it to a dealer to have a new impeller installed. That was in March.
Thanks,

may want to replace the recycle valves. mine were bad and acted like yours changed them purred like a kitten after.

What's a recycle valve?

if you look on the manifold you will see small hoses the hoses are attached to recycle ( one way ) valves. the can be removed and blown thru if able to blow thru both ways it is bad and replace it ( cost is about 16 dollars a valve) your mechanic should check them as one of the first things as all they are is a very fine screen.

He means re-circ valves.