2007 Yamaha 150 4-Stroke

I recently bought a 150 Outboard in the crate, during the break in the motor seemed to work great, at around 20 hours the motor started to act up and will only turn up 3800rpm at WOT, where at first it would turn up 5800rpm at WOT. I tried hooking it up to a portable gas tank and no difference. The strange thing is while the motor is at idle putting the fast idle leaver up it sounds like it is running great and it jumps to 5000rpm like nothing, but as soon as you put it in gear and it is under a load it is like it has no power and it is gutless. There is now 28 hours on it and still doing the same thing and will only turn up 3800 max. Any sugestions?

Look at 2004 Yamaha power loss post I wrote, take a look at what I did it may help alot.

It is almost identicle to my problem, sounds like fuel

I have a 2004 F-150 with 458 hrs on it. It has started acting up and would lose power after running for a couple minutes at WOT. It acts like it is starving for fuel. I have drained the gas tank and cleaned it, replaced 10 micron fuel water seperator, replaced filter in front of motor, cleaned VST and screen in it, changed F-filter between primary fuel pumps to vst, injectors have been ultrasonically cleaned.