Mercury 300 HP promax

I am working on a mercury 300 hp promax it sat for 4 years with fuel in it I cleaned out the vapor seperater and sent the fuel injecters in and had them cleaned cause it wouldn't even start with that sludge.

Anyways it starts and idles well it reves up good in neutral but under load it wont even do 2000 RPM's wide open throttle. It does not miss just acts like that all she wrote.

there are no codes present and the computer tells me nothing spark is hot and fuel pressure is perfect any ideas?????

This thing is really pissing me off for all intesive purposes the f ing thing should run but has zero power and I am out of ideas I work on opti's all day long every day but I am not real familier with these motors but I am out of ideas

Thank you