acceleration problem
 

Hi just joined mf. have a E220cdi. it seems i have a problem. my car does not accelerate( it is a stick shift ). In the 1st gear it does not go over 30 kph. in second not over 50 kph and so on, no matter how much i press the pedal. It just does not cross a particular speed in a particular gear. Earlier i did not have this prob. It just sprung up!!! Any suggestions???????