Found the source of my idle issues!
Middle portside cyl no compression...motor ran fine, boat still went 70 with ease!
Piston is fine, rings are pinched on ex side.
Top piston had same compression as rest but exhibits the same marks and was likely next...
I think it must have overheated at some point before I owned it as it has never idled well for me.
It has 20 over WSM pistons in it.
Boring it 30 over, putting in 6 new WSM pistons.
Shaving a bit off the heads too.
Replacing poppet, and both thermostats. Have not removed tstats yet, hoping to find one stuck.
Had my injectors cleaned and the 3 portside double checked and they were good! However, one from starboard was bad. So I bought a new one from Yamaha.
Vid of my injectors