We changed the air filter and fuel
filters and did the Seafoam injector cleaning
via "filter method" and there was no vibration at idle. Hopefully it's the same when we test with the engine not warmed up.
Two things we noticed:
1) The air intake has a very strange design. There is a cone shaped air filter, but air can only enter via a small maybe 1.5in tube that extends off the filter housing? Wht have this large filter that can only intake through a tiny portion?
2) The old filter was completely degraded where said tube intake is with supposedly 100 hours on it. We requested a full service
when we bought the boat, but who knows if the actually did it.