1994 nissan micra, jerking and stuttering after driving for 10 miles?

I have 1994 nissan micra, which has began jerking and stuttering after 10 miles of driving. the car has had a service and distributor cleaned, but the problem still remains and the mechanic dont have a clue what the problem is. when the car starts to jerk and stutter it loses power slightly and revvs to get moving again. please help?