2012 SX240 Starboard engine fast idle

[msavold]

TL;DR version: starboard engine idles at 3000 rpm. Running ok when I put it away last fall... Thoughts?
Been a busy spring so haven't had a chance to get it in the water until this week. Family's here, thought I'd start engines before hauling it all the way to the ramp and... port engine running fine, starboard engine won't idle below 3000ish. Did drop down into the 2000s at one point and then in seconds jumped back up to 3000 without throttle movement.
* Throttle cam is moving fine - with cable and manually. In idle it's against the stop. Lubricated it just for giggles with no effect.
* Don't have diagnostic software so can't look at anything in that direction on my own.
* plugs are about a year old (last spring replacement) with next to no hours on them.
* hoses all seem to be connected to where they should be?
* on second thought, there were some rough idling sessions last season. Put those down to bad gas since the previous season we only put SEVEN hours on the boat (you know those summers when the times you can boat it's raining cats and dogs or too cold to go out?) but to me that doesn't explain what's happening now or why only one engine.
Any advice appreciated!

 

[Neutron]

If its running lean it will idle high, but it really needs to be hooked up to yds to see the data and compare to the good running engine.
Is it a smooth idle?

 

[msavold]

Yup. Rock steady on 3000 - for as long as I dared before engine temp warning since it's on the hose.
Going to have a look at the throttle body in the morning with my fingers crossed?

 

[Neutron]

Yup. Rock steady on 3000 - for as long as I dared before engine temp warning since it's on the hose.
Going to have a look at the throttle body in the morning with my fingers crossed?

It shouldn't get a engine temp warning on the hose, thats another issue.

 

[msavold]

I'm hoping that's my fault - I was running it through the Salt Away dispenser and there may have been a bit of a pinch in that crappy hose. Also there was a bit of a "what the hell is it doing?" moment on my part. And tried to throttle up in forward and reverse to see if it was a stuck cable but each time it settled back down to a rock steady 3k. After about 2 minutes, temp warning. Sigh.