Suzuki 2003 140df issues

[SDUB407]

I have changed water pump impeller, thermostat and water pressure relief. There is a steady tell tale stream but when I idle looking for Bait it takes about a minute before it does it but the temp alarm comes on motor begins to run rough. I can turn it off and restart and runs fine as long as you are underway even if it's just barely in gear. Also the engine doesn't want to get over 5 to 5200 rpm. This weekend it acted like it had an oversized prop because it wouldn't get on plane. It eventually would but was taking way longer than normal. Engine has new plugs and a new coil as well. Typically get 41 to 42mph out of boat but right now 30 is all I can get once on plane. Any help would be appreciated thanks.

Sean

[catacom225]

Sound like the dreaded engine holder scenario, try running it with the engine cowl off. could be choking on exhaust gasses

[Cameron]

I am having similar issues with my 2016 300 hp. Usually runs at 141 F but lately running at 4500rpm at 165F -175F. I changed the thermostats and still running at the 165F-175F at 4500 rpm. Any suggestions would be appreciated.