Vibration at a certain RPM?

Hello, my vehicle listed above, 2.0 TDI (CR) makes a vibration at 2,000 rpm and at 4000rpm the whole car vibrates like it’s a v8 truck. It only makes when the car is loaded, at any speed when reaches 1900-2000rpm a vibration like sound comes from the engine bay, if you accelerate pass that range, the sound stops. Firstly I thought it could be an engine buffer, so we changed all three (left, middle, right) to new ones. The vibration is the same. (Full revision was done: oil and filters and timing belt has been changed) The next thing was the double mass flywheel since it has been running with the original clutch, got changed but the vibration is still the same. Not even the REV range where the vibration was has changed, nothing. I’m worried about that the crankshaft could be the problem... Does anyone ever meet a problem like this?