300 hpdi bucking loosing rpm

Last year I had fuel issues with my twin 300hpdi. This spring I drained the tank, flushed it clean, replaced the water separator, 10 micron filter on the side, VST filter and the medium pressure filter. I flushed the fuel lines coming from the tank to the engine. Fuel was clean. I took it out for the first time today. Putted through the harbor then started to slowly open up the throttle. I gradually built rpm until about 4200. I noticed the starboard engine loosing RPM. Eventually it started bucking really hard and could not get over 2200rpm. I could not get the port over 4200. Is it possible that this is a result of the VST tank being vapor locked or is there something else that I am missing. I also noticed that the fuel consumption rate was very erratic. In the past, during idling through the harbor it would say 0.8 to 0.9 gph. Now it would bounce between 0 and 6 or so. Any help would be great