Mercruiser RPM Issue

[capemaychef]

After fishing the cape may reef yesterday, we stopped to attempt a drift at the Wildwood lump for an early flounder...when I slowed the boat down the port engine wouldn't drop below 1800 rpm. I revved the engine and it brought it back to 1200-1400 where it wouldn't go any lower. Turn the engines off fished about 5 minutes, went to turn them over and once again the port was around 1500 this time...our throttle linkage has some play it in and sometimes gets stuck at full throttle(not a good feeling)...I am hoping that this is a minor adjustment under with the throttle linkage, when the engine is in neutral, it is at it's normal 800 but when it's in gear it is up around 1200-1400. Engines are 2000 5.7 Mercruiser Horizons with about 630hrs. Any help would be greatly appreciated. Thank you

[parkersc]

I cant imagine why it would change only in gear. You should have someone watch the carb linkage when you put the boat in gear, it shouldn't move. I would suspect the problem is in the shifter but it should be easy to isolate.

[capemaychef]

Thanks for the reply, yea I am thinking it is in the shifter with the cables...the engines are fuel injected.