It does not go from revolutions

My van, a Mercedes Vito 120cdi, after walking it seems that when heating, the engine is denyed, does not go from revolutions. In fifth it does not exceed two thousand revolutions and 110km/h, in the fourth it does not exceed 80km/h. I have consulted in two workshops and have not been able to say why? I don't know what to do

Do you turn on the motor fault? I suspect that you are entering the motor protection mode but in the workshop nothing more plug the diagnosis the failure would review the sleeves of the admission and intercooler that does not have losses state filter air and load battery to go discarding