Loss of power

Moin Moin, I hope someone can help me here. I drive Fiat Marea Weekend JTD 105 (!!!LEIDER I hate this car and I hate FIAT!!!). If the car is driven out at the beginning the final speed is just over 160 (normally it should be 180). Gradually it commutes to 150 and then it gurgles through the other side. LMM is brand new and the exhaust gas recirculation has made me close to the engine through a sheet metal. Everything helps nothing. it is that the AGR valve is so messed up directly at the crusher? Otherwise which causes of error are possible? Achja: Error codes were not stored… all empty Thank you in advance