Opel Combo without strength

Good afternoon,
I have an Opel Combo 1.3 CDTI, which I bought a few months ago. When it goes to about 2000 rpm, it seems that it dies and when you step on the accelerator, it takes to react. I have taken it to the mechanic, but they have not found the failure or even connecting it to the machine, no failure comes out, and the truth is no longer what you do to find the problem.
Do any of you have an idea that may be the failure?

Greetings and thanks

Hi friend Mira suggest ATU mechanic to check the diesel injection pump and check the injectors if they are well calibrated or not and also as a advice you also see in the pump or take it still banks workshop to calibrate it and verify the draft of this

Look at the EGR valve, you can cancel it with an iron sheet

What kilomeraje has, is drowning in low the escape not to be?

The EGR does not eliminate it in case such changing, check the turbo to see if the West Gate opens the filters as they are that time they have if it is intercooler would have to check the same.