I recently installed new 871 blowers on my boat, I ran into this issue when we were setting the timing. 1 engine is completely fine, the other will not go below 2000 RPM's if I rev it up to 2500. Shut it off, restart it, idles fine can blip the throttle no problem, returns to idle, can rev up some and it returns to idle, but if I go over @ 2500 it won't come back down unless I shut it off and restart. I replaced the TPS first then both IAC's (with off brand because thats what they had local). Any ideas would be much appreciated. Thanks a lot, Zack

make sure the throttle cable is pushing the linkage all the way shut.

We did, it looked like it wasn't, so we adjusted it a little. I can double check it though.

This driving on the water or on the trailer ?

Disregard

This is just sitting in the water, not out going down the lake. Not in gear.