06 4 stroke 150 cutting out @ WOT need help

i have a 150 4 stroke with a jet foot that normally has a running rpm of 51-5200 rpm at full throttle about a month ago it started to cut out and bust up really bad if you back off the throttle to around 48-4900 it clears up and runs fine but the least bit of throttle past that and the motor goes crazy.it has been taken to the marina they put a yamaha separator on it changed the little bowl filter under the cowl took a fuel sample out of the tank and told me that there was no water in it that i must have gotten all out running it.i carried it to the lake and it ran fine for 15-20 minutes,went to catch some shad and the motor idled then for about another 30 minutes,when i went to leave it was terrible and for the rest of the night it would cutout at full throttle if you back off about a quarter of an inch or so to 48-4900 it ran perfect all night. called the marina they told me it was more water in the fuel.can anyone help me on this?:

[boats.net]

Remove the fuel filter on side of engine and check it for water. Have the tach checked, that does have a rev limiter that activates at 6200-6400 rpm's and jet drives will hit the rev limiter if impeller is worn.