'05 Ford F350 Diesel has a hard vibration when accelerating past 1½-2 RPM's with decreased power.

As I was driving today, my truck started to get this heavy vibration when I was accelerating past 1½-2 RPM's. It doesn't matter if I'm at a higher speed or a lower speed, only happens at that RPM. It also has reduced power at that RPM. Vibrations seem to decrease when I let my foot off of the gas. I am pulling a trailer but it isn't a very big load. Don't know if pulling it has anything to do with the problem. Talked to someone and they mentioned that it sounds like water in the fuel? So maybe my fuel filters are bad and just need to be replaced?
This truck has been giving me lots of problems lately. Just replaced the turbos about 8 months ago. Replaced the engine (with a refurbished engine) about 7 months ago.