Have a 2000 150 evinrude ficht with 1,800 hrs. Motor is bogging when trying to plane, wont go over 1800 rpm in gear, however will rev out on the trailer in gear with hose /flushing. Have changed and indexed all plugs replaced thermostats, fuel filters, and run ethanol free fuel only. Motor has a lot of hours need to make it through one more season before repowering. Any ideas?