problem finding on a mercedes benz b170
i have a 2006 mercedes benz b170 non turbo this car was driving smooth then suddenly after service the car wasnt exceeding 50km/hr even if i press down the gas pedal and its been 2months now driving it like that but jst yeasterday i noticed that its now exeeding that 50km what can be the problem ,that same yeasterday it does limit again once after that i just put it on parking and excelarate it and i put it back on drive after that it was driving nice again