Reduction in speed after 3300rpm on 2002 225 4 stroke

I have a 2002 225hp 4 stroke engine that has been having problems when running at 3300rpm and higher. Engine runs fine at idle speed and a little higher but when we go to take off and get up on plane after a minute or so the engine suddenly reduces speed back to idle. We have checked for water in the gas but none. Originally thought it might be one of the fuel pumps. Can't seem to find the problem. Any suggestions on where to look.

[boats.net]

Pump fuel primer bulb to see if engine picks up rpm's(mechanical fuel pump may be bad). Connect engine to a portable gas tank to see if runs better(may have fuel restriction in fuel tank or hose). Test Vapor sepatator fuel pressure to see if losing pressure(VST may need cleaning or bad elect. fuel pump).