High idle in cool water

[foreveryoung]

I have twin 1998 ox66 250's and last year at the end of the season I noticed that after running 10 miles to my fishing area and then *****ing around for awhile looking for fish when I took the engines out of gear they both were idling at 1000 rpm. I fish off the Del. coast and I thought it may be the cold water not letting the engine stay warm. This spring the engines are doing the same thing and water temp is 63. Could the thermostats be sticking open? Seems strange both engines started doing this at same time.

[boats.net]

Check throttle linkage on engine first to see if have sticking or corrosion issues with linkage not allowing to go back to idle position.