Hey guys, I'm pretty new here, I have a 1999 Maxum 2300SC with the 5.7 Mercruiser. Lately I have been experiencing some really strange idling issues. A couple weeks back it seemed to need to come up so we adjusted the idle higher. Yesterday it was idling fine for awhile then after cruising around for awhile it would idle SUPER high like 2000RPM when I would put it in neutral. And when I went to shut it off it was "dieseling".
Today I went over to the boat and brought the idle down a couple turns which seems to be good. I ran it for awhile in my slip and it stayed around 6-700RPM. I revved it up in "throttle only" and when brought back to neutral/idle it jumps up and idles around 1000RPM. If i manually reach in and move the rod it closes the throttle and the idle comes back down. Any ideas WTF could be going on? Why would it not close itself all the way when I put it in neutral?