My F90LA (new 2013) Yamaha 4 cy on my 24 ft pontoon boat runs good at rmp's below 4000. At 4000 and above, it runs ok for a few minutes then reduces rmp's to 3000 - to 3500. After a minute or so, the rpm's go back to the original level. It does this over and over. It has 75 hours run time...
