250 Ox66 ?? Please Help

I have a 2002 LX250TXRA and have now been experiencing some problems at crusing speeds. My initiate problem was that at 5400rpms the boat would just bogg down. Indicitive of a O2 Sensor problem that was changed. And it ran perfect during the test run.

I took the boat out the following weekend and after about running 15 minutes at 4200rpms the rpms started to fluctuate and fuel flow meter jumped around.

The following has been done and the problem is still here:

New Plugs
New VST Filter
New O2 Sensor
New Primer Bulb
New LP Fuel Pumps
New Fuel Filter
Checked tank intake and vent / no restrictions

Can the fuel injectors be cleaned on an 2002 EFI LX250TXRA or do they need to be sent out for servicing or replacment?

PLEASE HELP....ANY SUGGESTIONS

[boats.net]

May have a fuel restriction in fuel system which can be checked by connecting a portable fuel tank directly to fuel filter on engine and take it for a test run. It is better to send injectors off to have professional cleaned.