Motor not running full speed

[mike0429]

I have a 65hp evinrude and it start's and run's low speed great it's only when I go full throttle with it it just seem's like there is something holding it back. It ran great the week before and this time it started this and after heading back in it all of a sudden started running great for about 10 min. and then it strated doing it again I don't know if it might be a fouled plug or what. Any info that might help get it taken care of. Thanks

[ELGIN]

Check compression, then get engine warm by running it with water and test spark.